You mean developer of Mp3tag: Florian?
Or developers of WMA container format?
I took a shoot at another format [because I'm looking for another lossless format to use aside from FLAC]: WavPack
WV files seem to behave the same as MP3s and FLACs. There is no problem with unusual data that I use in the TRACK field. And I've also tested to same extend other fields in that format, with different signs
But the TRACK field WVA bug question remains: should or shouldn't it behave the same as MP3 / FLAC / WV in Mp3tag?