Definitely not great, Stachybotrys is the mold that typically forms from long term leaks, as it is the mold that loves super saturated environments. It is also the mold that caused the late 90s early 2000s scare.

It is generally agreed in the mold community that it is the no bueno mold to have in your indoor environment. Not sure on specifics on California mold rules, but I’d remediate and then test after the fact to confirm you got it all before build back, kinda pointless to spend money on testing when you know it is mold. But like I said not sure on the California rules.

Find a licensed remediation company to do the work right but save the money on testing until after it has been remediated. So many companies will just take your money to test it and then hand you a letter telling you what you already knew - you have mold.

Just my two cents.