"Who is its public" is a pretty easy question, actually: Anyone who speaks any of these four languages is its public. Unless someone convincingly proves the opposite, readers don't care whether it's "sr", "hr", sh", "bs", or "hbs" (or "cnr" ;).
I do think that given the current state of the software, a more practical solution would be to have one project in sr that would be more focused on Cyrillic, and another in hr, sh, or hbs, that would be more focused on Latin, but this still means that an hbs or sh is eligible.
I'm fine with both codes. "hbs" is cleaner according to the standards, but requires a bit of work, although it's really tiny, and it can be an opportunity to make the converter more generic. "sh" doesn't require any additional work, but in the current configuration, it doesn't have the converter enabled.
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Amir Elisha Aharoni · אָמִיר אֱלִישָׁע אַהֲרוֹנִי
http://aharoni.wordpress.com“We're living in pieces,
I want to live in peace.” – T. Moore