Mentioned here Wyatt's theory how he imagines fights are fought here >>54934
Perhaps we also should view the frontline based on that as well, because reports of fights are coming from the local HQs, they are reporting to the command of their parent unit. They report the locations where they are coming in contact with the enemy. Liek X woods, or Y road, or Z groups of houses. Except they can give gps coordinates.
But if we want to project their view onto a map, we more likely to get contact areas, instead of contact line. This could also help to solve the grey zone riddle. Ofc they still use grey zone as a way to hide captures.