renaming chests ingame via console or an openmw function.
1 way that came to my mind how it could maybe work would be, that it could be similar like new enchanted items which does create a new item itself. And a little script that removes the old one. So it should be used on empty ones only. I have no idea What openmw is capable of , maybe even much better than my proposal, so i'm just throwing this out there. It would be a very convenient and cool feature doing that ingame instead of CS.