I noticed this today.
I had to revert to a backup of the db but I doubt it's the problem.
I noticed few strings that I'm pretty sure were translated and when I click save nothing happens, the page reloads with normal success text and the translation is not saved.
Tried disabling all caches, etc... Noting helped UNTIL I remembered the recent fix in template compilation.
Please can somebody make a info text there saying " "Please enable Force compilation" when you make manual changes to the templates or translations through BO". This will help lot of merchants I think.