Git cherry-picking (rebasing, etc) is about applying patches to things. Those patches are based on snapshots and thus you can say "Apply the Y2..Cherry" diff to Head without a second thought.

There's no "history" to where Y2 or Cherry came from. If the patch applies, it applies.

Any problems due to that are to be resolved later.

It might be instructive to read up on rebase --onto and what that can do. Cherry pick is just a special case of that... mostly.