P.S. The problems we have with library filename mapping are a re-run of
the problems Linux and BSD distros have been experiencing with
filesystem layout for nearly three decades. Various proposals for
standardizing file locations have been made over the years. None of them
became universally accepted. In the end, the only system that is
convenient for distributors is if all pathnames used by a program are
configurable.

Unix provides mounts and symlinks as tools that users, sysadmins, and
distributors can use to work around breakage due to clashing
conventions. I'm almost certain that we'll end up needing similar tools
in Scheme, and for the same reasons.