“The Bitter Withy” doesn’t sound very Christ-like. :/
There's a whole raft of pious medieval legends that grew up around the infancy of Christ, since the Bible and for that matter sacred Tradition say next to nothing about it.
The medieval mind could leave no hole unfilled and no blank space unaccounted for. And sometimes what the ordinary folk used to fill the blank was not what we would consider "Christ-like".
But we can still enjoy it for what it is. And it does have a beautiful tune (at least my version does).