Looking at this thread again it seems like it was never fully resolved, since all the proposed solutions were dead ends for generating a list of the missing/corrupt files without downloading the full repository contents. The solution that does work was suggested by @alexweiss in another thread:
Essentially, the solution is to run:
restic backup --force
restic diff -v <known_good_snapshot> <last_snapshot>
Any missing or changed files can then be restored (using a series of --include flags with restic restore)