alchemy, I think you misunderstood something.
From your statement :
"" Like for making thief gloves(feather/leather rank 25) a fail should get me a rank 18 but since there is no rank 18, it jumps into the next lowered rank 14 Rosy Woolen Clothes which also has feather/leather based. ""

I believe you are making (Thief Gloves) using Feather boots + steel thorn bracer, am I right?
The rank drop is calculated from lowest rank of material used, not taken from what we will make.
So Feather Boots(rank 24) + steel thorn bracer(rank 22), you get Rosy woolen clothes(rank 14)
If you calculated it right, it is -8 rank drop from rank 22 to 14.
For black quill shoes I`m not sure cause never getting any of them even just now when I tried, just got that roxy woolen clothes until now
I kind of sure cause been studying formula for a year, am using own formula even making lvl 80++ equipment