Hi, read your post, and your coffee plant problem.
1) do not over water them, they only need to be kept damp
2) presumably you have them indoors: they like lots of fresh air. Possibly you have some chemicals ( air freshener, etc ) in your air at home, that they do not like??
3) keep them between 60F and 80F, ideally at 70F plus/minus 5F
4) under stress ( travelling from Hawaii ) coffee will shed all its leaves, and go into "hibernation" for a while; as long as the stem remains flexible, it may be alive: when fully dead, the stem will become brittle, and snap: then is the time to, sadly, pass them over to the compost gods.
I hope that you have been reading my articles about growing Blue Mountain coffee: a soon-coming episode is about growing the coffee from seeds: if you could contact me, directly ( using the e-mail address at the end of the articles ) I will send you the draft of the article, which may be of help.
As you know, coffee only grows in the tropics: and to grow it as far north as Quebec, could be a real problem. Temperature is very important, they die if it drops below 60F for more than a short time ( heated green house?? ) but I have no way of knowing how the annual variation in the day-light hours, affects them ( "sunlight", artificial lamps?? )
Fully dried "green bean" coffee, very rarely germinates; if you can get some, fresh, partly dried, beans should germinate; but be prepared to wait a long time, my coffee seeds take between 2 and 4 months to germinate, and that is in "ideal" conditions!!
Best wishes
Robin Plough.