I don't think there's anything inherently childish about comics as a medium? They have exactly the same capacity for literary value as any other medium. A large part of the conventions of the superhero genre, I'll grant, are pretty childish (the words "superhero" and "supervillain", for a start - using them to…

"it implies that non binary people would not being included if it were simply trans (short for transgender)"
…oh, that makes sense, although what I've heard from other non-binary people (whether dmab, dfab and/or intersex) is that they consider it necessary because they find that events and organisations that don't use…

Although the relevance of hair colour to Ron & family's characterisation is social context - it was repeatedly used as a weapon against them, as is often the case for ginger people in the real world and as is far more the case for trans* folks. The same isn't true for Harry and Hermione, so it actually wouldn't have…

All the Weasleys, idiot. The books also stated that Harry had dark brown hair, and the casting director got a dark-haired actor. I can't remember what was explicitly stated in the books about Hermione's appearance, but I'd have remembered if she was described as ginger because that would have seemed significant…

The books stated that the characters were ginger, so the casting director specifically got all-ginger actors for them. If they can do that then they can hire a trans woman to play a trans woman.

For many trans* folks, transition-related surgeries are indeed quite literally necessary to prevent death.

No, that's bullshit. It's only considered transmisogynistic by "transsexual separatists" who want to distance themselves from non-binary folks (and frequently anyone else who doesn't fit The Harry Benjamin Narrative as well as they feel they do, too)

So how is it different, then?