Do birthdays get celebrated in autumn?
ooo i have never considered this before! i had both of the same initial thoughts. especially because ... what is a year's time to an essentially immortal being? that's a blink. a yawn. (don't get me started on how immortality is not played around with enough in-universe. where are my characters who are just so bored of being alive. beron is like . a thousand years old or some shit right. no part of him is tired of living? i digress.) okay and i just had a bunch written about only doing intimate dinners annually and big galas on the decades or half-century — but as i got to the end, i talked myself over to the other side.
i think they do celebrate birthdays annually! because ... fuck alive, living that long is monotonous. birthdays probably aren't even about aging. they're excuses to have social functions, to have reasons to congregate, to have something new to look forward to. i feel like in autumn, they probably get really fantastical. especially because i don't think beron begrudges them much at all. because — exactly what your first point said — it's a means of displaying wealth, plentitude, status, power, etc. look how lavishly we can celebrate even something as trivial as aging. plus it gives beron a reason to have all of the nobility gathered unofficially and keep them close and keep them entertained and drunk and debauched and happy so they're less likely to cause him issues. also even gifting something publicly can be a valuable political move!