I thought one of the mains purposes of R6RS and its standard module
system was to allow more portable Scheme code.  How can that be
possibly achieved when one can't even portably access in R6RS one of
the most famous Scheme code bases?  How can that be achieved when you
can't reach an agreement on such a simple matter such as how to treat
numbers in module paths?

Come on, this one just lends itself naturally into a poll of sorts.
I'd vote for (import (srfi-n)).  If anyone has srfi/n/* for srfi-n,
write a wrapper for all that code...

Numbers shouldn't be allowed to start module names, for the same
reason as for identifiers.  Going against this quite universal rule is
like pulling a Microsoft, getting path separators like \ in a C/C++
written world and eternally suffering by writing paths like
"\\foo\\bar" in written code...