I don't know what you mean by dainty cities..
I will start off by saying that 4 gallons is much too small for -any- fish but a betta. I know you may have been told different by pet store people, or whatever, but let's face it they tend to not know a lot :D
Your celestial danios, could use a few more buddies, and need to be in at least 10 gallons.
Your sword needs at least 15 gallons of space, plus at least one friend.. If he had more room, hiding places, and a friend, I'm sure he'd be willing to come out and get to know you! :)
If you can get a 15-20 gallon tank for home, that would be the better place for these guys, and a betta for the 4 gallon, with some shrimp if it feels too empty. :)