I'm no Mospeada guru, but I have recently watched the series from beginning to end.
Inbit do seem to be limited in how far they can sense energy. However, they did somehow find earth from wherever in the galaxy they came from, whatever that implies. Robotech's babbling about Protoculture aside, what you see in the footage is played pretty much the same in Mospeade. A single H-90 powering up can be enough to draw their attention. In Mospeada, all of those "protoculture canisters" are actually HBT, a kind of hydrogen fuel. After occupying the planet, they hoard and control the supply of HBT as a way of controlling the remaining human population. In short, the techno babble changes, but the results stay the same.
I agree, we should go with the Mospeada Inbit, since it levels the playing field.