One reason the there are no good TTS programs for Hebrew is the overwhelming prevalence of acronyms in modern Hebrew speech. (Another reason is that the potential market is relatively tiny.)
I remember feeling that in English, acronyms are barely used..
> Initialisms are a subset of acronyms; acronym is accurate here.
I believe you have that inverted.
An abbreviation is a shortened version of a word or phrase, and encompasses both initialisms and acronyms. An initialism is pronounced one letter at a time.
Acronyms are a separate special case - an abbreviation that is pronounceable as a word unto itself.
> The broader sense of acronym inclusive of terms pronounced as the individual letters (such as "TNT") is sometimes criticized, but it is the term's original meaning[1] and is in common use.[2]
Source: I'm from Germany