Not sure if helpful but I always try to share when something works for me
I won a set of I believe Peyton Legacy and matching wallet in a very pretty green. The wallet had the most damage, some black and white stains that I had no clue what they were, but I mostly wanted the bag that only had a bit of wear at the bottom edges.
After using first the
Coach leather cleaner and my white rag turning brown, I saw that the white stuff was like some sticky residue and was cleaned, the leather was also clean but the black marks (there were some also under the white spots), was not going anywhere. I tried my trusted eraser that had cleaned spots and ink on other leathers, but nothing... Rubbing hard with the cleaner was starting to take the color, so.. I just tried this.
A toothpick dipped in the cleaner carefully rubbing/scrapping spot by spot and crease by crease, look at the result!
I still can not tell if it was ink, some kind of mildew, paint... but it worked and I am loving the wallet (mint inside).