I know this is in the spoiler forum, but this is pure speculation... Written in white, hi lite to read...
I have been spoiler free so far, and I'm trying to stay that way. I was looking at Vader's helmet and Gen Greivious' face. It looks like Ani takes some design elements from the good Gen. I'm specifically thinking of the 2 long things on GG's cheeks that end by his mouth; comparing them to the 2 points near Vader's "mouth". Also, a small similarity in the mouth area, the metal mouth /vocabulator covering.
Another thought... If Ani is taking design elements from GG, what else is he taking from him? Ani is supposed to be super attuned to droids and mechanical systems. Maybe Ani takes some of his body, or idea's of how to build cyborg appendages (like Ani's hand) better.
This is just some speculation, pleae don't reveal any plot or story points. Thanks!