I have the same kind of experience as you. Healer Quest works perfectly on Android (IAP + Leaderboards and achievements), but I'm still litterally STRUGGLING with iOS export. I first tried using Intel XDK (which I'm using for Android) but despite I had approval from Apple, the IAP weren't working.
Then I tried exporting with Phonegap Build, but now my submission was refused (2 times) because of Game Center... And I still wasn't able to test the IAP using Phonegap Build. With 1-2 weeks between each submission, it takes a lot of time, and I've been unable to use sandbox mode successfully up to now to test IAP without receiving official approval.
From my experience, it's impossible to get help on export to iOS problems on this forum. Most of my post on the subject either have received no reply, or unuseful onces. My guess is that most people simply don't know how to do it. I also haven't been able to find a recent tutorial about how to export to iOS with IAP working, while they are dozen of Android tutorials + the very active Intel XDK Crosswalk experiences thread. Guys from Intel are always ready to help, which makes exporting with XDK much easier.
I'll tell you when my game will be successfully exported to iOS, and will try to explain how I managed to do it (if it happens ^^').
Good luck !