Are humidity domes or tents important?
It really depends on the ambient humidity in the grow room / closet. Is it cold and dry or decently warm and humid? If its dry (under 40% humidity), I'd say you want a dome.
A good hint for taking firm cuttings is really drench the mother with light-bloom water a few hours before taking the cuttings.
Having said that, I don't use any humidity domes. I mist a few times a day for the first few days then once a day until about 8 days when they start to root.