Somehow Scala has a lot of the issues that I feared would have impacted Typescript by now (yet hasn't) so I'd be interested in comparing and contrast why Typescript isn't perceived as having the kinds of issues Scala does when on paper they sound similar in features and technical challenges.
Having worked on a lot of legacy codebases both creating and inheriting I'm quite interested in practices that balance rapidly prototyping and deploying systems and gracefully degrading when projects lose people and funding. It seems tragic to see so much of the work of our lives thrown away so fast.
So I'm here scratching my head at the point issues denoted in the OP wondering if I missed something critical about what makes Scala so different in its ecosystem conventions that a community couldn't fix over years. Even Node.js managed to work something out via Yarn
Java, Kotlin, C# and TypeScript are led by companies that want usage. Scala was and still is primarily an academic exercise. Same problems as with Haskell - the leadership are paid to add random optimised-for-sounding-clever ideas to the language, not design a language in the gestalt that optimises for user success.
In particular TypeScript is not a research language and therefore the documentation, marketing, leadership etc doesn't strongly emphasise convoluted FP type theory. That means the sort of people who really want to go wild with that stuff stay away.
I'm not an either/or kind of person and don't see why a language suitable for academic purposes can't be broadly useful in industry, but I would also agree that leadership that has little background in certain use cases may not design and orient the language accordingly.
I'm personally in the camp of "keep Scala huge and weird and multi-paradigm, but just make less breaking changes and focus all efforts on making the ecosystem more stable".
Also worth noting that Scala is not a "very big" language in any sense that I know of. It has a lot fewer features than C#, for instance. And probably a comparable amount to TypeScript.
One thing I find encouraging is that Scala features may become deprecated (either explicitly or de facto) if an overlapping feature is added that works 'better'. Examples I've come across are Manifest getting replaced by TypeTag and implicit coercions getting replaced by implicit classes.
It looked for me like someone wanted to add every existing language into one single language.