Hmmm. If you're doing the compilation yourself, I'd imagine you could rely on what browsers provide these days, and compile to what you need. For the kinds of data transformations that templates tend to need, I wouldn't imagine that you'd really find a utility library to be necessary. Check out the Svelte output, for example.
If anyone wants to take a look it's at tmzt.github.io/isymtope and github.com/tmzt/isymtope
The #cleanup-symbols branch is much further along and has a mostly working TodoMvc.