Here is a subtle detail about mifconv that has kept me puzzled for a while:
If you have SVG icons with both .svg and .svgt extensions in the same directory (assuming that one is the output of SVG2SVGT for the other), and then pass the name of the svgt icon to mifconv, e.g.
then mifconv will actually silently use the file Myicon.svg (note the missing "t") rather than the exact filename you specified. In other words, mifconv ignores the given extension completely, and uses its own search method (probably .svg, then .bmp) to look for source files first.
mifconv $(TARGETDIR)\Myicon.mif /c32 Myicon.svgt
Therefore, having both the .svg and .svgt files in the same directory, and distinguishing them by extension, is not a good idea, as you may pick up the non-SVGT version.
I keep wondering why SVG2SVGT isn't just made part of mifconv anyway, because having an interactive tool in between makes the whole production chain much more messy...