"I want a cuter bag."
The sentence as it is has a little ambiguity just because もっと could apply to the whole rest of the sentence or just to かわいい
〔〔もっとかわいい〕カバンが〕欲しいです。- I want (more cute) bags.
もっと〔かわいいカバンが〕欲しいです。- I want more (cute bags).
We can force もっと out of the subclause where it's getting attached to かわいい by moving it after:
But I think probably a comma (or an even subtler pause in speech) would also do:
jisho.org says that 鞄 is usually written using kana alone: かばん
i think, though duo introduced us to 鞄, it want's to steer us towards using kana for it.
this seems to apply to other words as well, where in earlier skills it would accept kana or kanji, it now insists on the more common one.