It seems that the list of weapons commonly known to elves has some errors. The most obvious of these is the omission of the longsword. Since elven elite warriors have that as a standard weapon, it seems like it must be an oversight for elves to not know how to make these.

I'm also not really convinced that elves shouldn't have composite shortbow technology. Elven elite warriors have Mounted Archery as a standard feat; this implies that (Mongol-like) they've mastered the art of firing from horseback. I believe historically that the Mongols invented the short composite bow for this reason.

Arguably the main reason to have composite bows of any kind is in order to make Mighty versions and take advantage of a Strength bonus, so perhaps the reasoning is that most elves won't have a Strength bonus (indeed, most will have a penalty). I believe this reasoning to be flawed, however, for two reasons.

The logic that runs "... elves wouldn't bother with this because most would not benefit from it ..." should conclude "... and so they invented the light crossbow." The idea of elves using bows rather than crossbows, though, is so pervasive in fantasy that I wouldn't dream of suggesting that. In any case we're not interested in the average elf; we're interested in what their trained elite warriors (the ones with Mounted Archery) are capable of. And these individuals - as 1st level fighters with a standard array - will have a Strength of 13 even after the elven penalty is applied, so they would definitely benefit from a Mighty composite shortbow.

The second reason builds on the first. Elves are intimately associated with archery; think of any elven warrior, and you're probably going to picture a bow in his hands (granted the Lord of the Rings movie was responsible for a lot of that, but the concept is much older than Peter Jackson). Given their stated high technology, it is reasonable to suppose that they've figured out the best way to make bows. Even the much more primitive Vos - a race that have no particular affinity for archery - have the ability to make composite shortbows.

I understand that the Khinasi are supposed to be really good with bows, and I don't really have an issue with elves being restricted to composite shortbows rather than both types of composite bow, but it does seem a bit silly to me that a non-archer race of barbarians have invented something that an ancient clever race of archers haven't figured out yet.