The swarming is not so strange when you consider how long they've been confined.
I think Finman had it right several posts ago, that you just don't have enough bees. Just up the road from you many of mine are in a similar position. 3 weeks ago just 8 or 9 frames of brood, sure they're 16-18 frames of brood now but none of that brood is out foraging yet. Hives like that are going to have missed out on at least the first half of the main flow. Fortunately it seems to be quite a long flow there's 3 or 4 weeks left in it thanks to the quantities of rain we've had. Hives in that condition will catch the end of the main flow and be in great shape for Heather but you've been expecting too much from the limited numbers of older foragers in the hive.
Quantities of undrawn supers is a pain when you increase year on year( or crush and strain in good heather years). Best bet is to spread your drawn( wet stored) comb out amongst your boxes next spring . That way they'll be up into those supers like rats up a drain pipe. There's probably no more than 5 undrawn frames from the 90 new super boxes I added this year doing it this way.