So once a v1 torrent downloads, generate the v2 hybrid hashes and be able to share to the v2 swarm too. Would this work?

Someone on a different board said converting a v1 to a hybrid changes the v1 info-hash, is this true? which seems disappointing on having a hybrid that isn't backward compatible with current swarms.

In any case you need 100% original shared data to generate v2 caches, v1 to v2 does not convertable itself. I don't now, how properly add v2 and preserve original v1. But you already can cros-seeding v2 independent.