I'm confused. It's meant to be C4-621 and Ayre but there's Nightfall in it.

MSLabo102 said in comment #2534861:

I'm confused. It's meant to be C4-621 and Ayre but there's Nightfall in it.

In NG++, There's ALLMIND's analysis program. One of the entry was in fact NIGHTFALL Raven, and completing it grants the HC-2000/BC SHADE EYE part that Raven uses.
Since for the rest, Raven uses a C-2000 frame, its possible that C4-621 is using a Nightfall setup for the final battle here.