Why is word X not accepted?
Maranga’s dictionary was created by merging many different word game dictionaries, so anything acceptable in those will be acceptable here. But even so, some words and some variants are simply missing from those dictionaries.
English is a flexible language that permits us to construct new words using the rules of precedent and analogy. If the word elevate can be extended to elevation, then surely the word differentiate can be extended to differentiation by the same logic. But dictionaries are written by flawed humans who don’t always capture every constructable variation of a word they choose to include. And if that variant doesn’t appear in any dictionaries, it won’t appear in Maranga’s either. We considered adding such words to our dictionary as we discover them, but quickly realized that it would be a fool’s errand. No matter how many we add, there will always be more that we don’t catch. So instead of becoming a full time dictionary writing studio, we decided to leave that job to the experts.
This does means that you may find some reasonable-seeming words that are illegal in Maranga, but that’s no different than any other word game. The only thing I can promise is that, at the time of writing this note, Maranga had the most generous dictionary of any game we’ve ever played.