Adding RefToolbar to translatewiki

What is your intention as to how to handle translating?

• have a single message with the entire script including comments up for translation, or
• have individual messages extracted from the script and translated individually, general comments lost, and individual comments either lost, or taken from the message documentation (/qqq)?

How are abbreviations for languages having a separator inside mapped automatically? Could be either of:

• RefToolbarMessages-en-GB (dash)
• RefToolbarMessages-en_GB (underscore)

Would it not be more convenient to use:

• MediaWiki:RefToolbarMessages.js/zxx (standard)

rather than:

• MediaWiki:RefToolbarMessages-zxx.js (special, new) ?

I don't know whether or not that would be working, but including localized messages via {{int:RefToolbarMessages.js}} would be a way to avoid an extra server request and few lines of code.

P.S. I could not find the english messages being used anywhere, nor are there messages in any other language. I suggest to have a working prototype of the multilingual js part with at least two languages before taking concrete steps to make translations here.
P.P.S. Since there are likely more gadgets in more wikis with similar demand, it's certainly wise to make a design sufficiently universal and simple to copy.