Drafted a r7rs implementation:
https://git.sr.ht/~abcdw/guile-ares-rs/tree/master/item/src/guile/srfi/srfi-269-draft.scm

The are 3 minor issues:

1. There is no "location" in r7rs, so I've set it to #f by default.

2. There is no way to set the value of parameter except
parameterize. And because there is no atomic variables in r7rs, I've
just provided set-test-runner! and relied on guile's (parameter-name
param-value) syntax for implementation.

3. There is no define-public helper in r7rs, so I used just a usual
define for implementation define-suite.  Not sure what to do here,
probably we can just adjust SRFI-269 and tell that define-suite doesn't
have to make a symbol being exported.  And we can adjust discovery
mechanism of test runners to look up for private variables in test
modules or something like this.

Also, there are a few SRFI-64 tests, it's not a complete suite, but at
least something to check the implementation against.

https://git.sr.ht/~abcdw/guile-ares-rs/tree/master/item/tests/guile/srfi/srfi-269-draft-test.scm

--
Best regards,
Andrew Tropin