Oh god.
I mean, it's not insurmountable, but just imagining the amount of tokens makes me wanna barf a little.
Like, here's an excerpt from the first language file I found on my computer:
[T_WORD:DATE_VERB:rusama]
Now, let's try it out with some stuff to facilitate poetry and other language.
First of all, obviously we need conjugation rules to preserve our sanity:
[TRANSLATION:TROLL]
[VERB_PRESENT:o:i:u:u:a:n] first person singular, first person plural, second singular, second plural, third singular, third plural
[VERB_PAST:o:i:u:u:a:n] troll words all have exactly 6 letters. I figure this is a good example mostly to show the difficulty, heh.
[VERB_FUTURE:o:i:u:u:a:n] Same for all tenses because I'm lazy and, again, six letters.
[VERB_PARTICIPLE:e:t] past participle, present participle; but then, the game already has this.
Second, we need our verb.
[T_WORD:DATE_VERB:rusam:REGULAR] what kind of language would this be without irregular verbs? Some sort of conlang?... wait a minute
[SYLLABLES_PRESENT:roo-sah-moh:roo-sah-mee:roo-sah-moo:roo-sah-moo:roo-sah-mah:roo-sah-min] I guess it'll just assume that identical syllables will rhyme in this system.
[SYLLABLES_PAST:roo-sah-moh:roo-sah-mee:roo-sah-moo:roo-sah-moo:roo-sah-mah:roo-sah-min] I mean, this is obviously a dumb way to go about it, but whatever, silly example.
[SYLLABLES_FUTURE:roo-sah-moh:roo-sah-mee:roo-sah-moo:roo-sah-moo:roo-sah-mah:roo-sah-min]
[SYLLABLES_PARTICIPLE:roo-sah-may:roo-sahmt]
And that's just off the top of my head, there's more that's important. The game already organizes words by theme in language_SYM.txt and each individual word is given certain parts of speech in the files, and this isn't going at all into other such things, such as number, gender (though that's probably not a problem for dwarven poetry, heh), tense, case, mood or voice.
The system could probably just include default behaviors for case/conjugation/tense etc. and you'll end up with elven esperanto or whatever, but in general it'd just be far harder for modders to make their own languages. The pronunciation I guess you can apply rules to as well, so that's nice, but in general it seems like something... again, not insurmountable, but horrifically tedious. I know some people enjoy that kind of thing (I know quite a few do!), but it'd be a bit odd to require a bunch of wikipedia time for a language.
On the other hand, materials are pretty ludicrous right now, so it fits right in.