After thinking about it, the sender of a monero actually *would* know that information, except the node identifiers. A monero transaction knows which pubkey is the "real" spender -- their own pubkey is the real spender -- and they know the recipient's address, because the spender derived it from the recipient's public key. They also know what amount they sent and what fee they paid. So the only "extra" information he got from the LN transaction was info about the recipient's node's name and ip address. And if I had used my own node (which has no public channels) he wouldn't have even gotten *that* info. The privacy on LN really is very good if you don't use a custodian.