Back prior to the paid name changes, one of the things they did not allow was a trademarked name.
A friend was given an account by a different friend and tried to get the name of the mage changed.
So he did a ticket on another account complaining that it was a trademarked (drug).
The GM said you need to get the trademark holder to complain in writing.

Same friend asked a GM about ascii symbols in names, specifically accents over letters.
As of this month, the reply was to the effect... they were prohibited characters at one point.
But currently there's nothing against accents over your toons name.
Éñäñà is currently an allowed name, that's purely an example name though.