I have a problem with the first word of lesson 1: “mwyn” or is it “moen” or is it “moyn”. “Want”? It’s not in my dictionary, nor is it online in Cysgeir. I would use “eisiau” Why don’t you?
The course teaches Welsh as it is naturally spoken, and moyn is widely used in southern Welsh. It’s a contraction of ymofyn, hence your difficulty finding it in dictionaries. If you are accustomed to using eisiau, you might want to switch your setting to the northern variant of the course, because that’s the word they use there.
Pob lwc! 
However, you’ll also get very northern versions of other words, e.g. dallt for ‘understand’ instead of deall as is said in the south, plus hogan and hogyn for ‘girl’ and ‘boy’, so it depends where you live which region of Welsh is more suitable for you.