It seems I never created this ticket despite writing the description for it...

Right now we have front/back of a release, but no way to mark the front/back of individual types, e.g. front/back of booklet, front/back of medium, front/back of obi...

Overloading the existing front/back types is not appropriate, because that leads to very ambiguous sets of types. Take "front+back+booklet" for example. What does that represent? It could be:
1. the front of the release, the back of the release and part of the booklet
2. the back of the release and the front of the booklet
3. the front of the release and the back of the booklet
4. the front of the release which is also the back of the booklet
5. the back of the release which is also the front of the booklet
6. the front of the booklet and the back of the booklet

The example I had in mind was actually number 5 - back of the release which is also the front of the booklet. If we could specify front/back of individual types, this would become back+booklet(front), which would only have two interpretations (not perfect but certainly an improvement):
1. the back of the release and the front of the booklet
2. the back of the release which is also the front of the booklet

Front/back is one of the most common reasons to use the comment field that I've seen, so it would make sense to store this information in a more structured way.