For purposes of discussion, I will assume you are using queer as in same sex. In my own campaigns it’s not really been any more of an issue. Concubines can be male or female, free folk are able to do as they please, nobles even more so.
I don’t think you will run into a many PTSD issues as you think. Slavery is common, it’s a way of life and for most, it’s all they have ever known. For those who have never known freedom it’s just the way it is. Many would like freedom, but don’t seriously think they will attain it and trying just leads to pain. Better to do as expected and make the best of it. For those who were free and have become slaves, I imagine it’s more traumatic, especially if they were a noble, but free folk deep down knew it was a possibility. PTSD comes from a traumatic experience, you don’t see as much trauma is those who’ entire life has been that way.
In general I doubt same sex issues come up all that much. Historically speaking, it’s only relatively recently that it’s become a big deal, much of it driven by those with the power to impose their beliefs on others. What you need to think of then is how to the SMs, nobles, and trade houses view it?
Concubines are well looked after, I see no reason a queer concubine would be treated differently. The sexual abuse is no more than any other concubine and the status of concubine may even be preferred over that of a common slave. The biggest worry the concubine has is not how he or she will be treated but instead have they pleased their owner. A concubine that succeeds may be lucky enough to be one of the rare freed slaves when their master grows tired of them. They can at least hope to become concubines of favored gladiators, become domestic slaves, or at least killed (or sacrificed to the dragon). Far worse to become a common slave farmer or laborer and used by your fellow slaves you were once so high above. One thing to keep in mind is how concubines would interact with marriage laws.
In my own campaigns I’d run something like this:
Balic: Male partnering are common, with nobles, templars, and even free folk “fostering” their sons with older men in order to learn a trade. Fathers spend as much time looking for a suitable man for his son as for his daughter. Unlike marriages these relationships officially end once the boy comes of age and is able to support himself. This does not always mean the two end their relationship, but it is typically frowned upon for two men with that much of an age difference to continue. The younger male is considered a something of a failure as is his sponsor. Relationships between men of a similar age is commonplace with no stigma attached and is not considered to break any marriage vows. Females are discouraged from forming intimate relationships with others until after they are married, at which time they often form these relationships with those their husband find suitable. Baltic does not recognize same gender marriages but also does not recognize same gender relationships as infidelity. Baltic slaves have no say in any “marriage” which is only for procreation as arranged by their owners, but often find comfort where they can.
Draj: Same gender pairings in Draj are illegal. Once married, infidelity is death, at any level of society Same gender relationships before marriage do occur and those Draji who are serious about each other often never marry and live with the stigma or leave the city rather then be put to death for cheating. Concubines of both genders exist, but are given up upon marriage.
Gulg: Same gender pairings are common among all levels of Gulg society prior to marriage so long as it stays inside the dagada. Same gender marriages are forbidden and once married the couple is expected to be completely monogamous except during dagada celebrations and city wide festival days. Slaves are viewed as animals by all but the nobles so are never used as concubines although they are not discouraged from enjoying each other, same gender or not. Nobles occasionally grow fond enough of a specific slave to become intimate and these pairings are typically ones that span the lifetime of the noble. The noble/slave pairing is the only one that can transcend the bonds of marriage since aside from the specific noble and slave an animal can’t break a marriage vow.
Nibenay: One of the most open cities, same gender pairings are very common both inside and outside of marriage. Among the free, husbands and wives share each other as the feeling takes them. For the free, same gender matches tend to favor female, while nobles tend to favor males. Same gender marriages are scorned as much as so called “love marriages” but relationships within the confines are marriage are not leading to many same gender pairings attempting to convince the master of marriage to arrange a marriage with the other partner. Among slaves, females are discouraged from same gender relationships while males are encouraged. This is due to the children born becoming the property of the female’s owner. Among the monasteries, same gender pairings are common since they are single gender institutions. Marriages are annulled upon joining the monasteries although they may be reinstated upon leaving.
Raam: Same gender pairings are legal and somewhat common within caste bounds. They are looked upon no differently than same gender pairings. Before Abalach-Re’s death these pairings were typically as consensual as any other but with the rise of the the new power blocs people are willing to do anything for protection.
Tyr: Same gender relationships have never been an issue in the city. Nearly as open as Nibenay in this regard except traditionally a marriage is only a pair. As in Nibenay among slaves, females are discouraged from same gender relationships amongst each other while males are encouraged. This is due to the children born becoming the property of the female’s owner.
Urik: Same gender marriages are illegal in the city but relations outside of marriage are the business of only those involved so long as no laws are broken. Concubines of both genders are purchased and used as desired however female concubines are the most common. Within the bonds of marriage female intimacy is more common than male. Military regulations prohibit men from engaging in intimate acts with one another with the punishment of castration. While not every man is part of the military, they can be called on and few are willing to take the chance. Hamanu’s code also proscribes punishments for men cheating with a married woman but there is no current law against a woman and a married woman.
Outside the Tyr Region:
Eldaarich: Same gender marriages are illegal but infidelity is common. Same gender relationships are as likely as not, the people are just looking for comfort where they can find it. They are however quick to betray if they can gain advantage.
Kurn: Same gender marriages and relationships are legal. The people of Kurn do not meddle in the personal lives of others.
Kalidnay: Same gender relationships were common in Kalidnay. Kalid-Ma’s love of changing shapes and genders trickled down to all levels of society. With a strong focus on metamophs it was not uncommon for the person you were intimate with to start the night as a male and finish as female.
Yaramuke: Considered a den of depravity where anything went, same gender liaisons were common at all levels.
Saaragar: Happiness must be maintained. If same gender relations make you happy, it’s allowed, so long as no one in the relationship is unhappy.
Trade Houses: The trade houses do not involve themselves in the relationships of their people outside the highest levels. Anything is for sale, so same gender intimacy is common.
Aarakocra: Aarakocra are intimate with whoever they choose. They prefer to choose a single partner to spend their lives with regardless of gender.
Elves: The Elven tendency to live in the moment continues to intimate relations. Same gender pairings are as common as not.
Dwarves: Among free dwarves, same gender relationships are rare, but supported by the clan when it does occur. Among slaves it is even more rare as the slaves owner typically keeps a tight control on dwarven interactions.
Half-Elves: Half Elves tend to take intimacy where they can get it, regardless of gender. They have a strong need to belong.
Half-Giants: Half-Giants look to those around them. A Half-Giant in Nibeney can be very open to same gender intimacy but that same half giant traveling in Urik can change it’s mind. Typically only true love lasts beyond these swings.
Halflings: Halflings are promiscuous regardless of gender. Marriages are unusual but soul mates can be of any gender.
Muls: Muls tend do to as their master’s will. Free Mul’s often continue with the same mentality after they escape.
Pterrans: Pterrans are non-sexual except during mating season. At this time they mate only with the opposite gender. They can form close relationships with either gender but do not act on them the way humans do.
Thri-Kreen: The bond of clutchmate acts almost as a replacement of intimacy. To the Kreen, humanoid preoccupation with sex as strange as sleep. Kreen mate with their closest clutchmate of opposite gender. It is a purely mechanical practice.