I agree, but there are no tips for Hawaiian yet. This came out to see if people were interested, and if they were, they would make it better. So it's new. I also heard from someone that "ua" is a past tense marker. I'm not sure "i" is because think about it. Lots of other excercises that weren't past tente had "i": "E iho i llo" (Go down) "Aia ka pāpale i ka papahele" "That hat is on the floor" There's more, I'm sure, I just can't think of any more right now. Hope this helps or gives you something to think about.
But none of your examples have the i before a verb in a negative sentence. It was specifically before a verb and in a negative sentence that they said made it past tense.
And there are tips for Hawaiian. I've learned a lot from the tips. They just don't have them on every level (yet, I hope). They have more on the beginning levels.