Started playing with this over the weekend and had errors with Item_Syndrome, which you just fixed - so thank you!
Now it seems to run with new gen world and 7 starting dwarfs without error.
However, I probably haven't placed the item specific code correctly as my dwarves are not "adjusting" the way I thought they would.
In items_pants.txt (in both DF raws and verified it appears in saves raw)
Added a syndrome underneath loincloth (and opposite direction under thong)
[ITEM_PANTS:ITEM_PANTS_LOINCLOTH]
[NAME:loincloth:loincloths]
[LAYER:UNDER]
[COVERAGE:50]
[LAYER_SIZE:10]
[LAYER_PERMIT:30]
[MATERIAL_SIZE:1]
[SOFT]
[LEATHER]
[STRUCTURAL_ELASTICITY_WOVEN_THREAD]
[SYNDROME]
[SYN_CLASS:DFHACK_ITEM_SYNDROME]
[CE_BODY_TRANSFORMATION:START:3]
[CE:CREATURE:DWARF:MALE]
Then created leather, cloth workshops made 7 of each and equipped a squad of all 7 dwarfs. All with a replace item uniform of just a Lioncloth. Verified they are wearing their "gear".
Unfortunately nothing ever happens even after a month of waiting and several cycles of item syndrome. The DFHACK output shows it checking units, but never comments about finding anything.
My first ever forum post and its to sex change my dwarfs - that's very troubling I think..
Thanks for you hard work!