I think Don's experience is a good example of what 'misting' really is. Cuban is waterproof, period. So what Don was experiencing was condensation being knocked off the underside of the fly.
Yes, I know people rave on about how their tent/tarp/fly either leaks or doesn't leak in a storm, and claim it couldn't possibly be condensation. Well, I have to say that in most cases their claims have to be simply ignored. Under the right conditions you get condensation on the inside of a fly and rain knocks it off in a mist.
Now, that does NOT mean silnylon can't leak under pressure. Unfortunately current American-made 'dry-look' silnylon is not made to be waterproof for our needs. It is made to hold air in bulk, for sports parachutes and for those idiot blow-up advertising figures you see by the side of the road or on roof-tops. That's all. The stuff leaks at about 10 - 15 kPa (about 1 - 1.5 m water head). Yes, I have done a lot of proper pressure testing.
Of course, if your leak is coming from a seam, well, it's leaking. Sure.
The old 'wet-look' silnylon was waterproof, up to about 70 kPa or 7 m water head. But you can't get it any more.
There are some Asian versions which have a similar pressure rating of 10 - 15 kPa, and there are some other Asian versions which are GOOD (70+ kPa). But the latter are very hard to source. Sorry - I do not have a source at this stage. I WISH!