I don’t think recompiling for template changes is as unreasonable as you depict. It’s a standard technique in various languages, though I acknowledge that they’re mostly not languages that compile to native code, but rather an IL (e.g. ASP.NET with Razor) where the compilation time is somewhat lower.

For a language like Rust, compilation times and tooling support mean that the technique is perhaps not ready for prime time, but it’s fundamentally a perfectly sound technique, and can produce wondrous developer ergonomics (again I cite Razor).

There’s something quite incongruous about using dynamically-typed and basically uncheckable template language when you’re doing the rest of the code in Rust.