Hi!
You mean the MediaWiki message processing code? This would probably be
Yes, exactly.
powerful enough for units as well, but it works based on message strings that look a bit like MW template calls. Someone has to enter such strings for all units (and languages). This would be doable but the added power comes at the price of more difficult editing of such message strings instead of plain labels.
True. OTOH, we already have non-plain strings in the database - e.g. math formulae - so that would be another example of such strings. It's not ideal but would be a start, and maybe we can have some gadgets later to deal with it :)
Oh yes :) Russian is one, but I'm sure there are others.
Forgive my ignorance; I was not able to read the example you gave there.
Sorry, it's hard to give examples in foreign languages that would be comprehensible :) The gist of it is that Russian, as many other inflected languages, changes nouns by grammatical case, and uses different cases for different number of items (i.e. 1, 2, and 5 will use three different cases). Labels are of course in singular nominative case, which is wrong for many numbers.