The cotton ball is superfluous imo, I think a cut-up volcano liquid pad is cleaner, better, more sterile, etc... But all that is really only necessary fore most vapes if you're using oils. Normal screens can handle Bubble/kief...
Couldn't you simply place the kief by itself within the ELB? Isn't its mesh suitably fine? Even if it gums up in a day or 4, you can just ISO wash/torch them. If that isn't feasible then sandwiching it between conventional screens or using the Volcano pad (cut up or just compressed) should work.
With all due respect, I always hated the idea of mixing concentrates with herb or ABV, smoking or vaping, it's always seemed like a big unhappy compromise. I've subsisted on nothing but bubble (bubble gum, mind you) out of the VHW for the last month or so, and if I were mixing it with ABV, I'd want to vomit. In attempting to properly get the coldwater to the depleted, uncombusted, extracted powder I'm after, the ABV would of been set into a sickening combusted carinogenic blaze well before I got to that point.
If the current ELB system can't handle concentrates easily than a little improvisation with conventional screens or the Volcano Liquid pad should make it possible. Sorry if this has already been discussed at length, I haven't been following this thread quite as closely as I would have liked.