Size isn't everything
The begonia and impatiens cuttings get proper pots, and a lesson is learned about size.
The trays the cuttings were sitting in turned out to be, for want of a better word, crap. No drainage, no base trays. They'll be repurposed as bonsai trainers, where a lack of ambition is less of a problem.
So the impatiens and begonia cuttings came out. The larger ones are a bit naff. The mix wasn't quite right either, but they are still alive, with teensy roots spotted and stems in fine fettle. They are visibly swelling, so something is happening at least. The largest begonia was a bit rotty, though it had managed one small feeder root.
All of them have gone into a better mix and into the tent. They stay, for science.
Lesson learned: take small cuttings from plants like these. As small as you can for the thing you want to do.
