We all agree terf has not been a useful term for a long time, it implies they're feminists, it implies they're for women, it reinforces their arguments that they're on the side of women and gives them space to hide their more extreme elements.
Why not something like cis-supremacist? Something that is far-right adjacent would be useful in making people properly make this connection, especially given who they're allying with lately.
I think this is the best suggestion because it also describes a lot of TERF activism. JKR's whole recent project has been opening women's shelters that exclude trans women. She frames it as being purely about helping cis women, and not transphobic. This is similar to modern white supremacy, where most of them will claim that they're not racist, they just want to help their own people or whatever, like the 14 words slogan. Of course, as soon as either white supremacists or cis supremacists get sufficiently radicalized, the genocidal rhetoric comes out, but the smarter ones keep that in check to try and appeal to moderates.