Not everything from years ago needs changed to fit in with the "everyone needs catered for" modern way of doing things.
This is not a good hill to die on. It seems you don't even realize this isn't a new character. She is years old and well-established. Her near-death and mutation were a major plot twist, and a well-constructed one.
Did it bother you when April, in various turtles stories, learned martial arts and became a ninja as well?
The classic turtles aren't even being changed, replaced, or even
vaguely affected. An existing character who happens to be a woman who can use weapons got a similar mutation.
In a franchise with hundreds of mutants of every species, gender, and origin.
The irony is that the narrative you're trying to force this into would be more fitting if, for example, Jenny had been given a a painter's name and retconned as the lost sister of the four turtles or something.