I'll have to correct you on that. The wiki doesn't blindly follow whatever Yen Press comes up with, seeing as they have ignored actual official spellings on numerous occasions. However, neither do we just go with whatever fan translations came up with, especially when their variants don't really make sense (e.g., we have changed Schuberg to Zuberg, since the former was misleading pronunciation-wise).
Naming on the wiki is decided through community discussions. In the case of Renly, we decided to go with the Yen Press version, as the fan translation had multiple variants anyway (multiple translators came up with their own versions), so going with Yen Press was an easier way to resolve the issue.