Adywan has access to a physical performer with a film quality Threepio suit so it may be possible to remove Jar-Jar and film the actor in similar locations so the reflections on the suit match the existing material.
Filming the actor infront of set shots rear projected onto a screen would have a similar effect of creating plausible reflections to aid fitting the suit into the footage. In ROTS they did a rather good job of correcting the reflections to remove cameras etc. I’m not saying it would be easy but Ady does seem to like a challenge and other edit artists do too so there is probably an old school solution to many of these idea proposals.
I think the solution to that is just to make 3P0 dirty, that’s how they did it in the OT