One thing I think worth considering is the distinction between the configuration that is done at install time and the configuration that is done (by the user) at run time.
This proposal seems to support only installer configuration, not configuration by the person running the program.
Honestly, I'm not convinced that this set of operations meets a general need, but I could be convinced.
I don't like the idea of site-wide installation, because I typically run multiple, not consistent, configurations of CL.
E.g., for one project there is a set of known-stable, but out of date, libraries. For another that is more actively being developed (as opposed to being maintained), I use some of the same libraries in bleeding edge form.
Related to that, this proposal seems tied to the "link farm" style of registry management, which is deprecated as of ASDF 2.
Best, r