I agree with most of your points. But I think a rewrite is almost never a good idea.
I am writing a react frontend for discourse, but I dont intend it to be a replacement for the ember frontend.
It is more an addition for a very specific use case instead of a reiteration of the same thing. The reason is that I want to make the UI more adaptable to web3 experiments. For this it is more fitting to have an alternative frontend. I recon the custom wizard plugin also goes the route of a separate ember frontend. ( because the functionality is … well … custom 
… so it is reasonable to do it like this )
I have one repo where I have the react frontend with vite:
https://github.com/spirobel/web3-building-blocks-editor
and then I have a second repo where I pull in the build outputs of the first one in the public assets folder of a discourse plugin.
https://github.com/spirobel/web3-building-blocks
I also registered in your forum. If you have any questions let me know 
