Hello, it would be very nice if the hidden skill bonus could be implemented into CraftSim. Here is a video with some info on what it does/why it's relevant https://www.youtube.com/watch?v=bcMKDfaI9oY

For the actual numbers it seems like you have an equal chance of 1/6 to get +0/1/2/3/4/5% of the recipe's base difficulty as bonus skill. This can push some crafts into being profitable that would otherwise not be (for example some stuff that can be crafted at 3 skill below T3 with everything maxed out).
This should definitely be an opt-in experimental feature for now since we don't know for sure how it works.

you will be happy to hear that I am actually right now implementing it ^^
I made a post on reddit just recently
https://www.reddit.com/r/woweconomy/comments/10sipem/hsv_formula/?ref=share&ref_source=link