But this way, yes she lost the life of her son, but no she didn’t lose him in spirit. (This way, the addition of a Ben force ghost at the end would compound her success, and act as a sweet-end-of-bittersweet fulfilment/subversion of her vision.)
The lesson took three generations - Anakin’s failiure, Leia’s middle ground, and Luke finally getting it enough to pass it on. While I agree that it doesn’t quite land here in terms of the character ramifications for Leia and Ben, I think the broader message of the saga here is very strong, and should win out.