Yate support multiple in artists, album artists and every other field where it makes sense.

You have to read up on the multi-value delimiter which is by default ;;;

You can use Help>Search Yate help to locate the following articles:

Multiple Items and Multiple Values
The Multi-Value Delimiter, Fields and Application Lists

... and far more. Every action statement as well as the UI is multi value aware. Lists can be generated, manually or automatically so that you can use the menu to the right of a field to append values:

See the help for Settings-Lists for additional information.

All multi value items are properly encoded for the appropriate audio file type when the files are written.

As far as featuring goes there are multiple variants ot there: featuring, feat. ft. and ft to name a few. There are actions on the resources web page to convert featuring sequences to multiple artists properly encoded.

Basically, using the application defaults an album artist field of Jack;;;Jill represents two artists: Jack and Jill

With few audio file exceptions, the ;;; sequences are replaced with appropriate encodings in the files.

No trouble. Those custom fields will definitely mess up the files. Certainly FLAC files where those are the standard mappings.