An interesting thought for the future is if wasm will make other languages viable on the web. It would be interesting to see if anything else picks up steam as a serious competitor to JavaScript.
It sounds like you should invest some time in learning to program python in a pythonic way. If you are trying to build stuff using tons of design patterns factory patterns, you are doing it wrong. Most of those where made to work around limitations of type-systems which aren’t there in python, and naturally you end up having issues solving things like that when you don’t have typing. (Which you do still have with mypy, but as you say you’re not using that). At the end of the day you are using python and there must be a better way! though just like anything else you need to dedicate time to lean not just the syntax but also how to effectively use the language without needlessly over complicating things.