I agree with Dake.
Sum up, for me, source should be written by official language. For some cases, here I will say for Japanese. Some vn games doesn't give us an exact romanized name/source that you must forcely use Japanese/Unicode for source in Osu!. Yeah, it's sure that you can't find an exact romanized one. What will you do now? Translate by Google-sama and use romanized from it. I'm sure that Developers won't feel good when seeing a thing which is wrong with him. Also, the translated one also isn't perfect. You know, Japanese is a difficult language with many different pronouciations, space and no space in romanized source will creat different pronouciations. It is really dangerous. So, source should always be romanized isn't great at all.
It isn't also a problem that be called as "should" or "shouldn't". If you can find an exact romanized source or you believe that it is exact one and it is official, then add to source, for repeat cases. You can't do it and realize that the unicode is official instead, then keep unicode to source.