Some of the challenges I encountered while working on the AIR/GoogleHealth project:
- learning the Google Data API
- learning the Google Health API which rests on top of the Data API
- (re) figuring out some of AIR's limitations and features
In my experience this is pretty standard when dealing with new languages and platforms. 15 years on, still a struggle - but then probably one should be worried when one becomes too proficient in a language/platform because it's already obsolete by then.