I had always gone by the assumption that all of us would use just the standard Roman/Latin alphabet, so no special letters like the Spanish Ñ, the German ß, or the Norwegian Ø. Just the standard 26 letters that everyone in many languages (especially English) would be familiar with.
Honestly, this is meant to be just a fun game, and I hate to see it get ruined because of some technical trickery. There's plenty of words and names to choose from that use only the standard letters. There's no need to make things so overly complicated.