I think its very limiting to say LGBTQ characters can only be in romantic stories and of the few LGBTQ characters there are in magic who been featured in the lore, only Chandra and Nissa had a romantic story arc.
A big issue is that sexuality is only really a relevant characteristic to a character when it is on display. I'm not saying it isn't an inherent characteristic, but if it isn't directly relevant to a scene at hand, it shouldn't be brought up. Because it's irrelevant. (This extends to any expression of sexuality, not exclusively representational material)
So, unless it is saying something else about the character, that they are flirty or awkward, then it's going to come across as extremely ham fisted to bring it up just to say it./quote]
While I agree with you on principal, we need to think of an unfair double standard when it comes to LGBTQ characters. Being a cis straight white male is often treated as the default and unless stated otherwise characters will most often be though of as that "default". And due to this "default" thinking and media/creators doing stuff like queer baiting you have to have some sort of out right way of saying or showing they are LGBTQ that often leads to "extremely ham fisted to bring it up just to say it" or ends up so vague, hard to tell if they are meant to be LGBTQ. Kaya*, Will, Saheeli and Huatli are have been hinted to be not-straight but due to the vagueness and the Chandra/Nissa mess it makes it hard to tell if these are are meant to be LGBTQ or not.
Personally for the kinda of story magic is telling I think it can be causal as a male character saying he had a male lover in the past, has a male lover/husband/ect waiting for him back at home (like with Ral) and/or saying they find another male character attractive. Thats all causal stuff I think can inform characters without going over the top and its typically what magics use of sexuality reaches.
*Separate note this might also be why we are seeing this announcement now with Kaldheim, they might solidify the hints that Kaya is into women.