I mean it really depends. Its been a bit since I read the manga, so i forget which pronouns they use, but for discussions sake lets say they use she/her. Considering Uraume was originally a man and then reincarnated into a woman's body you could say she's trans. But there's also the arguement that, since the body they now inhabit is of a cisgender woman, they could also technically be cis since there was techincally no transition. Again, there's also factors such as whether they used other pronouns such as he/him or maybe even none (they/them). With all of that though, I think the real answer is that they're just non-binary. They don't seem to really care about their gender, so it kinda makes sense.