This is one reason Gea has lots of examples in the repository. It's an area of active development—I'm working on adding compiler support for more and more patterns. Basically, since we can analyze the code statically, and follow the dependencies even if they are destructured, we can create proxies or special handlers for each situation. It's a tiring job and unfortunately there's no one global, easy solution, especially as you pointed out, some of these patterns don't work in proxies. But I believe we cover an important base of idiomatic JavaScript right now, and I'm continuing with new releases to improve the compiler's handling on more exotic ways to write JavaScript.

Of course, one down-side of the compiler approach is, for example, if there's a statement you want to make reactive whose signature is only resolved in runtime (like a computed property name) it's practically impossible to wire. But Gea exposes enough of the underlying component structure so it's kind of straightforward for a developer to manually write an observer for these cases, and do the updates to static properties (that are rendered) in runtime.

Hope this clarifies the approach.