Here's two hours of a trans person explaining why JKR sucks. Should cover all the bases. And an article detailing her transphobia, using direct quotes from her if reading is more your jam.
I'll have to read that more thoroughly a bit later, but too clarify once more, this article details her own explicit wishes for trans people to die, yes? Like, she actually says that?
She does not support trans people and is one of the most prominent anti-trans personalities https://www.youtube.com/watch?v=EmT0i0xG6zg
You saying "she supports trans people" is either your credulous acceptance of propaganda machine she funds (best case) or you are part of it (worst case)
She has offered to bank roll the legal battles of a woman who openly advocates for trans genocide, and that's only one of her most recent actions against the interests of trans people. You're right that she has articulated her position well enough, but her position is absolutely not being supportive of trans people. I suggest you take a look at these videos if you want more info on the matter: