Closure
Oh well :-)
It took a while to get those moths (and, in fact, I sort of cheated -- I was merely looking for a list of levels that had moths, but stumbled across the hint that the hub screen had a secret room -- which was easy to find once you knew there was one, and even easier if you had seen the developer note sitting in the middle of nowhere).

With the moth indicator on the doors active, I could now focus on finding the remaining moths. Some were easy, some not. Some of them were outright unfair, making the level so I thought I had to go "there", while in reality I had to go somewhere else and those lit branches didn't mean a thing at all :-)

Nonetheless, I've finally achieved closure. Literally, even :-) Doesn't happen on a lot of games.