Is “producer” a credit that should be applied to recordings or only to the release as a whole?
List them however they’re credited and depending on context. If it’s a pop-album, I would probably put them on the album level since they’re likely in a more “supervising” role of the artistic direction etc., while in hip hop it usually means that they made the beats on the individual tracks/recordings and as such I would likely relate them per-track/recording. However, if in doubt, put them on the release level. If you (or someone else) find out more at some later point, you can always edit the relationships at that point.
This is a classical release, and the producer is listed alongside performance location, dates, sound engineers, etc.
I’d add it to all recordings by default, same as the engineers, unless it’s executive production.