too lean ?

Well for lack of my knowledge of the fast 2.0 system I can’t be any more help but I can tell you how the few I’ve used work.
Things happen way too fast during a drive to tune on the fly. There are just too many parameters to try to keep an eye on. So what tuners do is “record” the data they are interested in making changes to. That’s a datalog. You can log any number of different things; rpm, afr, boost, etc etc. after your drive you can review the data in real time on the laptop making changes to whatever parameters do not match your “target” (what you want them to be). You then save the new tune and download it back to the ecu and make another drive and another log. Rinse and repeat. Make more sense?