I wouldnt keep two females together either. that just seems like too much of a risk. Call me old fashioned, but i have a pressure sprayer and i just spray my cages once daily. That works fine. Humidifiers/misters, things like that make for a nice effect, but theyre expensive and dont always do tha job as well as just plain spraying it.
auriculatus females can tend to be very agressive twords each other and twords males, ive never really heard of female leachies being kept in breeding groups so much as breeding pairs.
I have 1.2 and i plan to switch the male between the two female cages, to keep them from being kept together year round, and so that he gets to both females.
Also, the way i feel about the ammount of space that leachies demand, being such large arborial geckos, is that to keep a breeding group, you would need a decently large cage. I keep each of my leachies in a 1x2x3.5 cage, which roughly ends up being about 7 sq ft per animal. They are currently doing really well, and tho i could PROBABLY fit a trio in there, leachies are so expensive it just doesnt seem worth them being agressive twords eachother, damaging or killing eachother.
my rule of thumb with any animal is better safe then sorry. provide more then they need then the bare minimum. and theyll probably do better that way.
everyone has their own methods and advice. thats just mine.