The idea that Russia has a particular responsibility for the Russian communities outside Russia became a core part of the identity of Moscow’s foreign policy elite in the early 1990s and has been a key driver in the evolution of Russia’s approach to its neighbourhood.

I don't believe the sprockets and sprockets-rails maintainers (actually it's up to the Rails maintainers, see rails/rails#28430) currently consider it broken. (I am not a committer/maintainer on any of those projects). So there is no point in "waiting for someone else to fix" it; that is not going to happen (unless you can change their minds). You just need to figure out the right way to use sprockets 4 with rails as it is.

I'm okay with an overall design that allows people to plugin the parts they need in order to be able to generically support a compile-to-javascript language, but to bake in support for one singular solution because its popular is simply bad engineering.

TBH It is a bit disheartening to see this issue closed when all proposed solutions do not sufficiently solve the issue at hand, I really like svelte but if this is how feature requests are handled I am probably not going to use it in the future.