Just an update
The red bugs were nowhere to be seen for 8 weeks. Last Thursday I noticed my Alien Freckles Acro (the one most affected in the first infestation) was lightly covered in red bugs again.
Of course this is a week after I added 8 Emerald crabs to my tank. I managed to catch 6 of the Emeralds and move them to a QT. I treated the tank with the same dose (4 Salifert scoops) of Interceptor. 12 hours later I did a 25% water change, and added 1/4 liter of fresh carbon to the reactor. The next day I put the Emeralds back. The next day I lost 2 Emeralds, and one got stuck moulting his shell and also died.
Last night one more Emerald died - a week later. Weird. So now I'm down to 4. Interestingly enough the 4 I lost were the small ones, and the 4 big monsters that are banned to my sump seem fine. Last night I noticed a few red bugs on that dang Alien Freckles Acro again.
So I'm going to break off as much of the AF Acro I can (it is short growing and very encrusted), give it a 2 hour strong Interceptor bath, and put it in my Zoa tank. I will use a pipette with boiling water to kill the remaining part of that coral. I'm hoping I can get away without treating the tank again.