Luke did not train between movies, because he would have been back on Dagobah, but he wasn’t.
He doesn’t train with Yoda, it doesn’t mean he didn’t train at all. Pretty sure Yoda’s training wasn’t about choking people or using mind tricks 😉
(has he found that in the jedi books we later see in TLJ ? Or a Sith holocron he got somewhere ? Who knows…)