What you're basically asking for is a localised product based terminology respository. Or maybe it should only be product based if so indicated explicitely. We have no idea yet how to implement such a thing, or what it should be doing exactly. For now my advise is to create these manually as a subpage of your language portal, and refer from there.
Yes, indeed, it would be sort of a dictionary, albeit a very brief one --a cheatsheet, if you will--, containing only the core terms for the message group, so that it would fit into 2 or 3 lines of text. Then it could be embedded the same way the qqq files are right now. The idea is for it to work quite similarly to the current scheme of /qqq subpages. The pattern to look for would be slightly different, but the rest of the current implementation could be reused (I suppose). Or are there other obstacles I'm overlooking?
(As for your statement "it should only be product based if so indicated explicitely", yes, that would make sense if we were talking about a large dictionary, but the idea here is about very short lists of terms used by that specific product, and therefore tailored to it, which would make them not exactly reusable.)
A few remarks: "quick and small hacks" tend to turn into unworkable long term solutions. manually implementing this in qqq is not the way to go. There needs to be some process that will match words in the source message to defined terminology and translations so that everything works automagically.