@yole: I can try everything again in my personal project at home, try using latest versions of everything to see if it will be working.
The most success I had - for some time 2.1.2 + Kotlin 1.0.3 was working together in Android Studio, but always failing to build in command line with gradle, and we had to roll back to 2.0.0
If things will not be working - I could give you some private access to the project. It's not opensource, but I'm the owner of the code