That would be a solid interpretation were it not for the fact that I can coerce the linking to work and the tests to run as noted in this comment down in the other trouser-leg of the thread.

Yeah - I saw that comment after I posted ... and wondered ...
And etj has pointed out that "it's dynamic libraries EUMM can't find".

Still, to me it seems unreasonable to expect the build to work if EU::MM can't find those libraries - given (my assumption) that none of those linking directives will therefore be present in the build's "make" stage.
However, given my lack of understanding of MacOs processes, I should just shut up.

Cheers,
Rob