In some ways, it helps. You start to see similar issues arise and know what to look out for when you're launching a new runtime. In other ways, every language has its peculiarities and its own set of design considerations.
Launching/polishing a completely new language still takes a decent amount of work. Launching a new version of an existing language tends to be much quicker.
Maybe even just something for compiled languages like Go, Crystal, etc that will just run the binary?
Would you consider running a container that could be run like Cloud Functions? This container could run the binary that you create. It's not something that we support today but I'm curious whether this would meet your needs.
Does this mean we actually run the container ourselves on our GKE cluster or in a VM? Or do you mean a "container" runtime for Cloud Functions? Both would be interesting, but we'd prefer the latter since there would be less to manage. I'd be interested to see the performance of it.
This is something Cloud Native Buildpacks (buildpacks.io) are intended to make easy. We hang out on buildpacks.slack.com, if you'd like to come pick our brains.