you aren't going to believe what the cause was...
but before i spoil the ending, here's how i conducted my tests. note that in all cases, nwserver reported the module was loaded correctly. where i've noted 'ok' as the outcome, i was able to find the server successfully and log in to it and fiddle around.
1-area plain vanilla module started w/nwserver directly : ok
cep 2.6 starter module started w/nwserver directly : ok
plain vanilla module + nwnx : ok
cep 2.6 starter module + nwnx : ok
my test module (named 'x9.mod') + nwnx : server not found
my test module alone : server not found
renaming plain vanilla module to 'x9.mod' and retrying w/nwnx : server not found
renaming my test module to 'vanilla.mod' and retrying w/o nwnx : ok
renaming my test module to 'vanilla.mod' and retrying w/nwnx: ok
renaming vanilla module to 'a.mod' and retrying : server not found
renaming vanilla module to '123.mod' and retrying : ok
so it appears that nwserver will simply not publish a module whose name is shorter than 3 characters !
could i get a reality check here ? this seems bizarre, but that's the only conclusion i can come to given the results.
this appears to be endemic to nwserver itself and seems to have nothing to do w/nwnx. i can't say if it's some sort of side-effect between nwserver and the nwniab virtual box, because i don't have a genuine unix box to play around with.