Everything happened at a fast pace. The Montebras were in the process of charging from one end to the other end of Phoca Arena.
During this short but crucial interval, the two lancer mechs had to find a way to successfully drive their lances through the frames of the two opposing drone mechs.
The Montebras already solved one problem by using their electrical bolts to accurately distinguish the real mechs from the surrounding illusions.
There was nothing wrong with the visual illusions and the false emissions projected by the offensive fey. They had successfully fooled the relatively modest sensor systems of the Montebras, but they failed to take more physical detection methods into account!
Illusions were ultimately false and intangible in the end. There was no way for the luminar crystal cannon fey to produce the correct kind of response when they were inexplicably zapped by electric bolts.