"I create valid words but they won't be accepted by the game. Why?"
You probably have changed the dictionary language. Please check in Settings -> Change language if the language is set to DE (german) or EN (english) and adjust accordingly.
"I often see XXX instead of the real words when i play against other players. Why?"
That's because the parental Control is turned on. When the words of your opponent are so-called profanities they will be censored and displayed as XXX. In the Settings menu, you can switch this feature on or off.
"Will there be a completely ad-free version of the game?"
It's possible and depends on how big the demand is. The more requests we get, the more likely it is.