yeah those rooms have a limited range, I never used them, I believe you can pinpoint fragments with them.
Im still pretty early ingame (wiped my save when the game launched), Build my first seamoth, and just got my moonpool up and running. Im also near an geyser so Im going to try that thermal powerplant thingie. meanwhile looking for diamonds, so I can make my first cutter. Oh encountered my first Bleeder (currently checking out a wreck in sparse reef) , you really need to get them off from you quickly, took half my life.