You raise excellent points about clarity around seeds in a mix and goals for a project. Terminology for seed parentage in a mix would benefit from shorthand but doesn’t appear to need it. You can always fall back on a verbose description as long as that description comes from good understanding (and having clear shorthand terms won’t fix misunderstanding)
For project goals, I’m glad you’re anticipating the need for clearly describing trait groups. I had thought about this before but you made it much clearer. To use your terminology, if several growers are sending in seed from their lettuce landrace swarms, I’m personally probably happy to try all of it. We’ve barely grown domesticated lettuce before on our place before, so anything from this group is welcome. On the other hand, there might be a lot of bitter lettuce in my lettuce landrace swarm because I really like bitter lettuce. That might not be OK for a lot of people, so maybe there would be a “bitter-permissive” lettuce landrace swarm group that might be maintained separately from the main one.
I think how we identify and mix different interbreeding populations that might be attached to different projects with different goals is an important question, but as it’s a different question from the original purpose of this thread (as I understand it) I might suggest a different thread.