Need advice on vintage Schott B-3 restoration

I sent this jacket to Arrow Fabricare to restore. They seems to have left the back top panels untreated: https://imgur.com/6mtTxNI

They say I can send it back to get it matched, but I'm wondering if there's something I can use to do it myself. Also, in general, what's a good product to keep a jacket like this in good shape over time?

Thanks for all your help!