I think you’re being too hard on yourself. When you learned Vue all you were learning was a framework.
When you’re learning Elm, you’re learning a language (a very different language than you’re use to), a framework and eco-system.
You have to set expectations accordingly. It won’t happen as fast. But Elm is a long term investment. It changes how you think and code. I would suspect you need to code in it for couple of months before you can begin to think in Elm.