The current i18n structure and whatnot exists because of historical reasons; in 2007 or so there was no "SocialProfile", just "UserProfile", "UserStats", "SystemGifts", etc.
Only after this extension/these extensions were open-sourced in February 2008 they were merged into one extension called "SocialProfile". That being said, I'm fond of the current approach, because that way you don't need to wonder, "what module uses this i18n message? Is it used by UserGifts or UserWelcome?" but rather it's pretty obvious -- if you're looking at SocialProfile/UserProfile/i18n/en.json the messages are used by UserProfile.

As for qqq.json, if you want to add that, go ahead. I have been and I will remain opposed to qqq, not to message documentation. qqq is notoriously translatewiki.net-specific with a bunch of site-specific templates and whatnot in it; thus I see no point in having qqq exported back to the source code repository from translatewiki.net.
To my knowledge, translatewiki.net staff mandates extensions, skins and other MediaWiki-related things maintained on WMF git having a qqq file, which I disagree with. If and when translators have questions or requests related to some of the things I maintain, I'm more than happy to help them out -- that way "supporting" these extensions won't take any of TWN staff's precious time.
From a technical point of view, supporting a new MediaWiki extension or skin is literally a few lines in TWN config, assuming that hasn't somewhat recently changed. The problems here are mostly social, not technical.

I should note that in my view, a picture is worth a thousand word. Six pictures are worth of 6k words, and are more useful than vague descriptions in qqq.json. Likewise, there's the test wiki on Labs where users, translators and everyone else can play around with many of the social tools and whatnot.

Related links:

• Thread:Support/Please add support for SocialProfile on TWN
• Gerrit changeset #82393

Issue number #1 is not an issue.

For issue number #2, I'll just say that this is a requirement we have and we don't budge on it. Everyone else uses it, and we try our best to instruct how to use it. We are not very strict how it is used: you are free to use links or screenshots or whatever you want, making it less or more tailored for translatewiki.net. The concern is not staff time, but translator's time. It's not efficient for them to spend time reaching out the developers for information that could already be supplied via message documentation.

Change 574758 had a related patch set uploaded (by Jack Phoenix; owner: Jack Phoenix):
[mediawiki/extensions/SocialProfile@master] UserGifts: add i18n message documentation

https://gerrit.wikimedia.org/r/574758

Change 574758 merged by Jack Phoenix:
[mediawiki/extensions/SocialProfile@master] UserGifts: add i18n message documentation

https://gerrit.wikimedia.org/r/574758

Change 575233 had a related patch set uploaded (by Jack Phoenix; owner: Jack Phoenix):
[mediawiki/extensions/SocialProfile@master] UserStats: add i18n message documentation

https://gerrit.wikimedia.org/r/575233

Change 575233 merged by jenkins-bot:
[mediawiki/extensions/SocialProfile@master] UserStats: add i18n message documentation

https://gerrit.wikimedia.org/r/575233

Change 575238 had a related patch set uploaded (by Jack Phoenix; owner: Jack Phoenix):
[mediawiki/extensions/SocialProfile@master] SystemGifts: add i18n message documentation

https://gerrit.wikimedia.org/r/575238

Change 575238 merged by jenkins-bot:
[mediawiki/extensions/SocialProfile@master] SystemGifts: add i18n message documentation

https://gerrit.wikimedia.org/r/575238

Deployed on translatewiki.net some minutes ago: https://translatewiki.net/wiki/Special:Translate/ext-socialprofile-0-all