For me, the most important thing about a front, that makes it separate from the otherwise homeless threats on the home front, is the "Dark Future." Figure out what your threat represents (fear, decay, hunger, thirst, etc) and then think about "what is going to happen if nobody stops it from happening?"
Also, just because the cult belongs to a PC does not automatically place it in the home front, it could very well be a threat listed in a separate front. If the cult and this delusion seem to go well together, you have 2 threats in a front already, and you can figure out the others from there, or figure out the dark future they represent and then figure out the other threats. Once you have 3 or 4 threats ironed out, make a couple of countdown clocks for the over-all front to help push them along.
Personally, I am not the most organized with my fronts during play, but when the fiction steers toward one of my threats I have notes ready to pull up and deliver moves from that threat accordningly. Often I spend time after the session marking off my countdown clocks as I realize the moves for the threat types or general MC moves have naturally moved things in the direction of the clock.
Once you pass 9 on a Front clock, it's too late to stop it! Your PCs had their chance, now you give them a chance to run or brace for impact as the inevitable comes crashing down.