> is there a way for me to ascertain if JS ecosystem has calmed down and is more friendly to productive programmer workflow

I would reject the framing that suggests the ecosystem is not geared towards productivity. These frameworks allow developers to be more productive than ever, as I noted in another thread, these tools have been a proven success across every major tech company with a front-end presence, it's not just hype, there are demonstrable results.

> everybody does whatever they like and there are not many widely accepted good practices for JS project management

There are many widely accepted best practices, but thats a huge topic. Use of linters like eslint can ensure hundreds of best practices are enforced in your project, and type systems like flow/typescript are an indisputable boon to long-term software maintenance. A software project with types is always much easier to maintain than one without, and the upfront cost of thinking about your data structures in advance of writing your business logic is the technical debt equivalent of not carrying a month to month balance on your credit cards.

> I should just pick up a project idea from, say, RosettaGIT or TodoMVC, and try and implement them with a few different JS stacks (React / PReact / Vue / Svelte come to mind)

This is a great idea. Everyone has different opinions about these frameworks but they're all productive.

In my personal opinion, React is the best of those options because the JSX code-as-markup paradigm means that your application variables interpolate with your views seamlessly without the added complexity of a system for processing gigantic string templates with custom logic directives and custom template inclusion mechanisms. Svelte has some interesting new ideas with regard to preprocessing the views at build time that are pretty cool, but I still prefer React due to the string template thing I just mentioned. PReact is basically just a slimmer React, not much distinction in terms of the workflow. I find Vue to be the least appealing of the options you mentioned since it has poor TypeScript support and in most implementations relies heavily on string templates, but it is often regarded as the most accessible framework for newcomers. Those are just my personal opinions, I think any of those tools are solid and they all have beginner friendly options like create-react-app to help you get up and running quickly.

> am just wondering: is there a way for me to ascertain if JS ecosystem has calmed down and is more friendly to productive programmer workflow, or is still pretty much the Wild West and everybody does whatever they like and there are not many widely accepted good practices for JS project management?

There are widely accepted good practices, but the domains in which they are widely accepted are narrower than “JavaScript development”.

Each major front-end framework is something of a community of its own (often with sub-communities), and there are others.