Composers' names are missing from so many track listings. Could you allow users to submit this missing info?

Sorry,
We don't offer a way for users to add credit information to AllMusic, simply because we have no method of verifying the validity of what the person may put in there.

One thing you can try is to look at the releases tab of an album, and sometimes a different release may have more complete composer information.

For example, the main version of this album does seem to be missing the composers on the tracks, but if you look at the individual releases:
https://www.allmusic.com/album/sad-clowns-hillbillies-mw0003030540/releases

this one from 2017 does display composers:
https://www.allmusic.com/album/release/sad-clowns-hillbillies-mr0004712914