@blueshiftlabs: Thanks for testing it, and sorry that it doesn't work.
In fact, that error got me thinking that my statement "at least it should compile" must have obviously been wrong. And indeed, I had added the 5.2.0 libraries, but forgotten to remove the 5.1.2 ones - stupid me. After removing the 5.1.2 libraries from the project, I now get about 300 compile errors.
Bad, bad Amazon. Their even more aggressive obfuscation now seems to have again renamed classes and methods. This means that porting these things to the PW will be a lot of work, and I don't even know how to do it right now. Anyway, I can't start working on it before I receive my PW.