HT1 is fine by me, though perhaps there is less precedent for numerals in the prefix – dunno, and it’s not by any means a big deal to me. If we’re going with three characters with the nod to Hershey text, how about HTE for Hershey Text Extended, or Enhanced, or [gasp] Eggbot or [double gasp] Evil?. (It is extended, after all, because we’ve gone to a floating point representation from an integer.)
Additional question: are there any of the font names for which you have alternate suggestions? As you can guess, the names were completely off-the-cuff creations for which I have no great partisanship.