Hi Duncan,
There was no problem to work with Lambert 93 coordinates under WAsP11, but, ok, it is not possible under WAsP12; the problem i have is to transform roughness maps, from Lambert 93 to UTM; which is not easy.
Well, i was working with 2 PCs, one with WAsP11, and one with WAsP12, but only one now is left, with WAsP12; i asked WAsP support to know if i can install WAsP11 after WAsP 12 on my PC left, without answer at that time...
Best wishes