I need one more coin in Area 2. I've gotten this far without any help at all and I am really happy about that. It is so rewarding.

But now I have no choice.

I have mapped out Area 2 completely and I know where every door goes. The shortcut to Area 4 seems to have no benefit. I have a theory that I have to get to the coin through Area 4, because that area only has 3 coins to collect, while the other areas have 4, and that this 24th coin I have to get is technically in Area 2 and that is why there are 5 to collect in Area 2.

Does it have anything to do with this level which has a locked door but no key?
Using the shortcut to Area 4 from Area 2 didn't even give me a coin! It just sends me to that infuriating, pointless room! The walls are just not high enough to jump over, and the high ground doesn't seem to have any benefit!

I don't want to know the answer, I just want to know if I am on the right track. I just need a hint! Please help!