"Juni' heirloom mini-dwarf - blossom end rot conundrum

All the fruit on my Juni plants is currently being tossed due to blossom end rot, despite having steadily ramped up my watering over the past 2-3 weeks. I'm not sure what to do because they're now exhibiting both BER (suggesting the soil needs to be kept more moist) \*and\* leaf epinasty (suggesting overwatering/root rot). The seed packet said Juni toms do alright in 1-2 gallon pots, and the pot they're in has good drainage.

Any advice for next steps? These are prolific plants, setting fruit all over the place, and I hate to see it all going to waste. These are indoors being grown on a West-facing windowsill (NC, US zone 8a).

Including a pic of my other toms ("Candyberry" and "Carrot-Leaf Mini") on the same windowsill because they also have leaf epinasty but have not had the same issues with BER. All of the toms have very sturdy stems and leaves--the leaves are just curled down. I'm pretty sure the issue isn't high ethylene, because there's no heat running, and my lettuce on the same windowsill is still green and crispy despite some bolting.