Sure you haven't tried to store YYYY/DDMM? ID3 (for mp3) would use / as a separator. (The second looks rather than DDMM/YYYY to me though.)
I've changed it so TDAT/TYER are merged into one YYYY-MM-DD "date" field.
Unfortunately, it's still different from the behavior of the old fb2k versions so anything that relies on exact date strings will break (playcounts...).
Does that mean that the playback statistics (that is collected so far) will be reseted or what? That's shocking!
Does it make sense to save statistics to tag before installing new version and to reimport it after installing?
EDIT: After using Axone, it shows most of the metadata in an experimental frame. TDAT has the new number written (e.g. 2410) with the actual year in TORY and TYER (1995). I tagged most of my collection in Musicbrainz Picard software. What is the quickest and easiest way of fixing this mess?