Sorry for the lack of information from my part. I've duly noted your work. I just need to spend a few hours looking really hard at the standards, the code, checking what other compliant m4 say about translit, and then incorporate your patch.
I did know it was a problem with translit(), but I had absolutely no time tracking it down, so this helps a lot, and I'll be sure to fix m4 and autoconf>=2.65 soon. Thanks