For those interested in my nclearseam project linked above, I haven't touched in a while and I don't plan to improve it any further for now. I stopped mostly because the javascript backend for the Nim compiler is not good enough. I remember things like iterators were not properly supported in the javascript backend, and nclearseam needed to use features like this.
Still, this is an approach that I still value, but for the moment, I'll write my webapps with Svelte directly and integrate with a Nim backend if I need a backend. I also noticed that reactivity within the language as permitted by Svelte can be a nighmare to debug and for an application I made that used heavily the special Svelte syntax for reactive variables within the code, it made the application very very slow. Explicit reactivity around Svelte stores is I believe better and for those interested I expanded them here: <https://github.com/mildred/webmsg-webmail/blob/master/src/utils/store.js>