is any level of visible mold acceptable in a study cavity 2x6 wall with roxul in some spots there is small fuzzy white nodules around where fasteners have condensed during the winter and small amount of surface in lower cavities. debating about hepa vacuuming it with the festool mini and then spraying with shockwave a hydroperoxide mold killer spray and then spraying their encapsulating product might be over kill moisture problems are now solved and should repeat to give the mold any moisture and heat again

It's best to kill off as much of the spores as possible, since they can lie dormant for decades until conditions change. If you start out with a nearly-sterile wall cavity it will take much longer for any new colonies to get established if/when moisture finds it's way in.

Moisture is the main cause for mold formation. It becomes quite difficult to kill mold completely. Thus it is always better to keep precautions and prevent mold growth with the proper ventilation.