I believe Scotty is right....VFT's love it outdoors and the more sun you give em; the more vigorous they seem to get. Just to give a comparison, it sounds like your setup is roughly 5,000 lumens(closer to 4800 probably) at a narrow spectrum where a bright sunny day is 50,000 lumens at full spectrum. As long as they have some humidity and food you can expect to see noticeable growth during a photoperiod as small as 7 hours from personal experience. but in general VFT's to me are hardy plants and seem to tolerate things other cp's would find disagreeable minus light of course.
far as a suggestion....if you are available to do it would be to put them in the window as often as u can and back under the lights when there isn't any light in the window and def get a reflector.
Sundews sound like they are just getting used to the conditions...give them a few more days and they should start dewing again.