Maybe you could add several traits representing dragon's tail and potential variety. Some might be more powerful or longer others weaker or shorter. Some might also have spikes and such. I feel like tails are kinda forgotten with AGOT dragons even though they possess immense power besides the more clearer maw, flames and claws. A strike from a strong dragon tail can especially kill enemy soldiers or even dragon riders. But weak, short or poorly "armed" tail can prove to be a dangerous deficit. This especially since, tail is dragon's greatest rear defense, especially at ground but also in the air.

Honestly, really stupid trait that should be rlly rare or just a debug thing is to make a version of destined that lasts for 10 years

Okay this would be VERY a-canonical, but I think adding different breaths for different types of dragons would be awesome. Like frost breath for ice dragons, lightning breath for storm dragons, arcane breath for moon dragons, hydro breath for leviathans, etc. It would be mainly flavoring, but you could add special buffs to each type to make them more distinct. Like leviathans could boost travel speed and safety over water, and could increase the danger for war enemies.

Hey maybe something to do with eye sight. Keened eyed, giving combat or a health boost, clouded eye giving worse health or so. Can be on a scale being eagle eyed, keen eyed, nearsighted, clouded eyed.

Also another one that just popped into my head something related to sound produced by the wings. So silent flight giving health and combat effectiveness, while loud flight ups the dread, but lowering combat.

Sample:
Dragon_name flight is so silent it is said they can swoop down to mount knights, taking them without warning, just as an owl takes it's prey.

Dragon_name the flapping of their wings makes them know to all. The sound of drake produces with their wings is unnatural and other worldly, sending chills down the spin of it prey.

Half baked idea:
Also another education trait line. Showcasing how good of an ambush they are, or something related to flight distanced that lows time to travel and give another buff.

A trait that represent what the dragon love to eat will be interesting. For example cow, sheep, chicken, fish & etc. Each trait will have its own pros and con like fish which is abundance and make the dragon continuously grow bigger without stopping but super slow or cow/horse which is not a lot to spare but let the dragon grow bigger in a short amount of time. Love your work btw, thanks for all your time

Maybe a trait contrary of destinated, if the dragons limit its reached the new born dragons one of them converts into a cannibal, having a trait called "Dragon killer" which its basically cannibal but stronger to make it a menace to the established dragons and start the cleanising of them.