Only columns ending in the chosen suffix are read as taxa, so a column reported in some other unit is not converted, not renamed, and not modelled. It is carried through as though it were a measurement, which looks exactly like a taxon that simply was not counted.
Details
Worth catching for a second reason. Per square metre is an areal density, integrated through the water column; per cubic metre is a concentration at depth. Dividing each by its own number puts both "per one", but per m2 and per m3 remain different quantities, and one cannot be turned into the other without knowing the depth the tow integrated over. Two surveys reported in the two units cannot be pooled on the strength of both saying "per one".