Thank you so, so much, everyone.
It's really sweet of you all to care about Sophie and Casper.
I'm really exhausted and sore all over, so I'm sorry I can't reply to anything, but I wanted to let you all know that we had a really good and really thorough (and really long) appointment. The vet examined Sophie and took x-rays of her head and chest and she couldn't find anything that would explain the weird noises while breathing at all. Her nose is clean, her lungs are fine, there's nothing blocking or pressing on her airways, no tooth roots in the way of anything, nothing. So, that's good news, even though it's a bit of a mystery. The x-ray did show that she still has a lot of gas in her stomach even though she's been eating very well today, though, so we're going to go ahead with the plan and keep her on Emeprid for a long while. The vet said that it causes drowsiness in some bunnies, but that it's completely safe to give for a long time and won't make her guts lazy or anything like that. Another thing is that her molar spurs have gotten bigger, but the angle is such that they can't hurt her tongue (they're growing pretty much straight up), and since she's eating well now we'll see how it goes. They'll likely need to be taken care of in the future, though.
Casper ate some greens before our appointment, so that was encouraging, and the vet examined him and he's okay and his belly felt and sounded fine, so we're going to see if he'll keep eating now and keep him on gut motility meds for a few days, but he'll likely be okay. He started eating some hay as soon as we got home, and he had some more greens just now, too. His molar spurs haven't gotten any worse since April, so that's really good.
I think that's all...