@arghc As I recall, Owain and Glen were stated to be childhood friends, so they should be fairly similar in age.
If anything, I think the 'only 130' is in respect to their potential lifespans, not their actual ages - that is, that Owain was forgetting 130 is old age for a half-elf.
Other elves, meanwhile, we know nothing about. But you're right, there should be some of them that remember such things. Owain's parents, for a start, if either is still alive.