Well, it would certainly help if a modder could run stonesense and get a TODO list of what exactly is missing. I could probably do the creatures with perl; after all it would only need to recurse on one index.txt file, reading all the linked txt and xml files and building a hash of gameID="(.*)", then read the entire RAW directory putting all CREATURE:(.*) tokens in another hash, then compare the two. A more advanced check would also store CASTE:(.*) and TLCM_NOUN:(.*) just to make sure nothing is misspelled in the xmls. But my perl scripts are cumbersome despite my best efforts and I often need to re-learn how to use them, so having this as a part of stonesense or dfhack would be much easier for the modders.
BTW, it appears to me that 64x64 zoom="1" sprites offer a good compromise between clarity and ease of making by resizing images and probably use up a reasonable amount of memory.
While having animated and coloured dogs and cats increases variety, they look kinda funky when their body parts are different colours. A dog with a black head and brown torso looks a bit like a giant ant or something
It would help if we could have if-then-else in rules, but even a "not" would help a lot, for example with clothes.
Wearing helmet => display healmet
Not wearing helmet => display hair
Not wearing helmet, wearing bandana => display bandana.
And so on.
Hm, I think the wagons are missing, at least I get a brown W for EQUIPMENT_WAGON in a mod.