In Pathfinder 2e, for a different example, melee reach works on those non-Euclidean rules, while every other range/area measurement does the "every second diago

In Pathfinder 2e, for a different example, melee reach works on those non-Euclidean rules, while every other range/area measurement does the "every second diagonal square counts double" rule. So for that, you actually need both versions of radius measurement.