All the field relationships seem to be expressed in strings. This suggests that you might not be able to use auto-complete or build-time syntax or type checking on them. I like the general idea, but that would be a big downside if I'm understanding correctly.
You are correct, the reactive expressions are not statically checked at the moment, but we have an item in our roadmap to fix that. On the other hand, the runtime expressions evaluator does provide feedback in the form of error messages, so it doesn't fail silently.
If done properly, autocomplete w/ Typescript and string literals should work just fine.
We will indeed explore this approach, would be great to hear your thoughts too! Would you consider sharing some more insight by dropping a comment here? https://github.com/golemui/golemui/issues
In that case, it seems that the live demos in stackblitz have not been done properly.