The dog is now more or less a slave of your boyfriend as it was raised with too much hand activity and too little exercise or mental stimulation activity. I would not, I repeat not, treat an animal to train it and reliably expect it to understand either way. You are training the dog to expect treats when you come into it’s proximity. That is all. It will stop barking because it associates you with a good thing. It would work just as well if you would take the dog out for a walk, find something that it will respond to such as a scent and train it to track, climb a ladder, or type a letter. This nonsense of utilizing the Pavlovian response, ie, sticking a piece of food into it’s mouth or setting off a clicker, will not allow the dog to develop a normal relationship with you. But then, you have to have a normal relationship with the dog. Your boyfriend has to be involved in this, and he has to understand that he created this problem and now that the dog is anxiety bound to him, he has to figure out how to “unlock” the problem. Get him to play with the dog, create games, get down on his hands and knees and crawl around, get the dog to do the same and see if you can get a belly crawl, I do this with my labrador who is not a swimmer when she gets in the water and “walks” on her belly and excitedly say “swim Abby swim” and have been doing this her whole life (she is ten) and for the first time in her life she went for a swim, (we have just gotten a young female lab puppy), so she is feeling extra pressure to make me happy.
What I am saying is really watch the dog, play with the dog in a different dog categorical way, and no I would not expect you to run home from work six times a day for 20 minutes to run around with the dog! I don’t think you would be employed very long unless you can get a job running dogs around that can pay the bills. Use praise vocal praise effusively, wisely, but effusively, and really mean it.
The main thing I am saying is create new opportunities for the both of you to interact with and try and draw this dog out. He does not have a healthy relationship with the dog, it is not scarred for life. It can turn around, but the two of you have to become more creative.
For your sake, (I am a light sleeper too but I am much older and have gone through anxiety attacks from hormonal changes and lack of magnesium, to now chelation therapy for metal toxicity). Try a product called Zen (sorry that is the name) which is l-theanine and GABA. Helps loads and is not a pharmaceuticl. The dog may need to be medicated for a little while with something to take the edge off. You do not need to keep doing this once the tension is out of the household and you do not keep anticiplating that this will happen each night. If the dog is barking when you come home, ignore it, hard as it might be, until it at least subsides, ask the dog to sit in the crate (it has to be big enough), no shouting stop, mabe a little “easy, easy, it is okay”, nothing harsh just a little progress and take the dog out, both of you, go for a quiet walk and just love the dog together. It will take time. This is a high anxiety breed anyway and very challenging. It is very good to see someone cares enough for someone who likely has some challenges of his own given how he thought he should train the dog and not try to have it out over the dog going to live elsewhere. The solutions I recommended may not work, but I have yet to see treats as anything but a very short term, and very limited training application without creating a problem of obsession with hands and what you have in them. I have to admit, I have to wallop this lab puppy sometimes when she tries for the 100th time to bowl me over but she is completely oblivious or nearly so. Most of those herding dogs are not.
One last thought, is there a way to leave a soft radio on for the dog (I always use classical music only) so as to block out some of the noise and create a regular “environment” around the animal. All of you have gone through big changes, really, this is to be expected a bit but the hysteria, or mad aggressive barking is somewhat of a psychotic fit and as you have noted, not associated with anything but heightened anxiety that can ramp up into aggressity. The music will help.