Janet's approach seems a little strange to me in that it's opt-in rather than opt-out. In CL or Clojure, you just normally can't have this issue due to the package or namespace system (e.g. you have to go out of your way to define an anaphoric macro that will work anywhere). Clojure doesn't have a separate function namespace either, but since backquote will automatically qualify symbols with their ns unless you opt out, you don't need to use any strange (at least to me) unquoting approach.

The "separate package" issue is really a non-issue, especially in Clojure where you have a different namespace for every file. Some people prefer a separate package for every file in CL, but even with one-package-per-project, you only have to worry about your own code. Anyone redefining functions outside your package isn't going to cause any problems with your macros.