That's very cool. I hope if it becomes semi-pernanent that they're able to keep the balloons from hitting the Arecibo Radio Observatory with radio frequency interference.
The observatory is in a high altitude and remote part of the island. I'd be surprised if they get any coverage out there since it would make more sense to keep them over the more populated regions.
100,000 people live within a few miles of it, in the municipality with the same name. It's not all that far from the coast: