I can't add things at this point without mucking up the hardcoded fire lizards, but I can tweak the art.
Specifically, I can turn the "horns" graphic into a "head knobs" graphic. They're a bit like giraffe ossicones, is that right? Only laid further back? I can also add a couple of extra fingers.
Other than that... I think a lot of the variation in the art is justifiable!
1/ Lack of dorsal spines, lack of head knobs: a sign of youth. Those are exactly the sort of thing that only becomes prominent with age.
2/ The two nose designs were intended to be 'mouth' and 'beak', but they also work as (an attempt at) 'blunt' and 'wedge', so perhaps the 'blunt' model is a throwback.
3/ The frills... well, like you say, official art is justification enough. Failing that, perhaps they're the post-Thread Pern equivalent of fancy pigeons. ^_^
As far as the named f'lizard generator goes: believe me, the issue had occurred to me! But a build-your-own dragonlet generator (like the TARDIS generator) would be a different project.
One thing Kaitlyn realised immediately you can do with it is get it to show what you would be like as a fire lizard - Huinesoron is, appropriately, flaming - and I considered labelling it accordingly. I could still do that, and tweak the 'owned' f'lizards to fit, but I'm not sure how I'd cope with Menolly's. Randomise which one you get, maybe?
Oh, speaking of people with multiple fire lizards... Cain and Jaythe are in now. I think you'll like them. :)