Your gilding system is fucked up, the numbers on success chance displayed don't check out, the Credo bonus has no bearing on it, modifiers have no bearing on it.
You shat your pants on this one both in theory and in craftsmanship. Bad jobr. Bad jobr. *hits with a rolled-up newspaper* Bad.
Get a proper RNG (not that "normal spread" vile abomination you have that allows for 100 heads and 0 tails in a row to be a real occurrence), check the modifiers' bearings, reeeeeally dig in with a fucking calculator or, better yet, ask someone educated in a fair intricacies of basic math to do so for you. I'm so done with this idiocy. You know you did bad, I thought you just had a bad creative decision but noooo, you done went and bugged your pile of crap as well.
TL;DR
The displayed chances of successful gilding either are not displayed correctly, not calculated correctly, or both; chance-increasing modifiers don't seem to apply; the calculation of success/rescue/failure is basically a boolean random, bar the credo "1st gild is a 100% success" bonus.