Should work in principle. Have a look at this test file
arch_inch_1_96_101inches.dxfBut there are issues. Not all matters of Imperials have been properly implemented, as LibreCAD is of European origin. For instance suppressing zero feet and zero inches is to no effect, also entering values in the Command Window with feet and inches don't work as expected. I think you have to recalculate to inches in advance for input, but I don't remember exactly.