My DH and I store our bikes inside on a leaning wall rack, so they are up off the floor and out of the way. We have a 2nd floor balcony, but in order to use the bikes, we needed to wrestle them inside and through the house to get out the door, anyway, so now they are closer to the door. It was too much hassle having them on the balcony.
I think from a theft standpoint, you are fine. Most bike thefts are thefts of opportunity -- someone walks by the street and sees an unsecured bike in an open garage, etc. It would take a lot of planning/effort to obtain a ladder, bring the ladder to your building, break the bike locks, get the bikes down the ladder without dropping/breaking them, and making off with both the ladder and the bikes. Honestly, that's gonna be a lot of effort (and a lot of risk) with not much payoff -- unless your bikes are obviously *super* expensive.
Maybe get a tarp/canvas to conceal the bikes from curious eyeballs on the street, plus it will protect the bikes from the elements. It won't be super pretty, but you also wont attract special notice from potential thieves.