High Hrothgar here just wandering about this mod called teh "Skyrim -Community- Uncapper by Elys". So I don't know if any of have come across it on your adventures through skyrim but does it only work with a new character or not? In the description of the mod it doesn't say anything about this so I was just wondering will I cooked myself some Apple Cabbage Stew here in Breezehome so if you have the knowledge please tell me if it'll work on an old character.

I cant think of a reason for it not to work with an existing character.

If you are worried just make a backup copy of your save before installing the uncapper. If it breaks anything, delete the uncapper files and load your backup save.