As of this patch, you no longer need all the coins to get 100%, you just need everything in the Extras menu unlocked (which means the cheat codes will now work if you can't find all the coins), all endings, secrets and the medallions.
Change to 100% Achievement
Build and release context
Steam update times within 24 hours of this post. Matching dates do not confirm which build it describes.
Build 7087167 · public branch
Steam updated · First observed