I'm running into this issue where everytime i re-edit something or want to add some new text to descriptions it's not displaying properly on my mod at all. Instead its giving me jumbled I's with noting readable.
This is usually because the encoding is incorrect. The correct encoding is UTF-16 LE (with BOM, I think, if your editor is that specific).
However, there's also an issue in that a lot of custom UCS text will not link properly ingame either. I've seen some mods do it, but never been able to find out how.