\, the Sanskrit virama, is not used. Of the 1370-odd ACIP texts I've got here, about 57% make it through the gauntlet (fewer if you demand a vowel or disambiguator on every stack of a non-Tibetan tsheg bar).
for ACIP, it'll easily be made to work as a perfect EWTS Wylie->Tibetan converter. It has an extensive suite of tests for the existing functionality.