I’ve found another one and managed to get my questions answered.
If you put all your coordinate data sheets in the “Low” container, you get a rift that transports you to Tractor Beam. When you hack it , it goes online and pulls all 6 hidden containers from the far side of the room (from where you land if you put coordinate sheets into “High” container and have to zip around to uncloack them). I MWD-ed there after looting to double-check. No cloaked containers were found.
On the first ball, it looks like “High” rift and manually uncloaking containers is a waste of time. Well, not necessarily so. It all depends on how tanked your ship is. There are three Remote defense Grid units. One at the start, one in the middle and one at the far end. When I did the tractor beam, I activated all three sentries. You can get one inactive, if you hack the Remote defense Grid unit nearby. On the other hand, when I did it the first time and used “High” rift , I had only one sentry on me – hacked Remote defense Grid unit at the start and one when I landed on the far side of the room. There might be a way to turn all of them off, but I didn’t manage to do it , even with hacking all three Remote defense Grid units. The one on the far side was on even after that.