I would hope you are aware of the picard/jaikoz tag mapping spreadsheet
The artists concept was taken from Jaikoz and Jaikoz already supports the albumartists field so I would hope you would map albumartists to these audio formats in the same way, these mappings are also defined in opensrc jaudiotagger project which is used by a number of applications (not just Jaikoz/SongKong) especially alot of Android applications.
Note for these new fields I have tried to use the exact same name for each format rather than varying it, this is to ensure better preservation of the fields because when transcoding files with tools like DBPoweramp for metadata fields it doesnt explicitly know about it would have same name in old and new format.
For example given a ID3 TXXX frame with description ABCDEF, if converting to .WMA it would create a field called ABCDEF not 'WM/ABCDEF' so that is why I map TXXX:ALBUMARTISTS to ALBUMARTISTS rather than WM/ABUMARTISTS. This way after converting such a file with dbpoweramp these new fields would still be recognised by applicatins that understood them, something that is not the case unfortunately with MusicBrainz Identifier fields,