Something I just happened to notice in passing is that main tag for the protagonist of Persona 4 is spelled as narukami yuu with two u's, while the tag for his Shadow is spelled with only one shadow yu. The spellings should match between the two of them, though which one to use may be a bit up for debate so I wanted to hear what others had to say before making any sort of BUR for it.
Going by topic #6952, it looks like the main tag was spelled as Yuu based on romanization policy. However as far as I know his name is consistently spelled as Yu in official English releases that use it (For example the character select screen and UI for the Persona 4 Arena games, and I also see it spelled as Yu on the dvd case for Persona 4 The Animation that I have). Personally I'd be in favor of switching to using Yu for the tag.