I agree it could become quiet difficult, but only if you make it that way.
The way I see it is you have a check list, separate to the QA type thing, whereby you install a module and and test it, as it meets the standards the list is checked and the rating given.
The QA team then as you say at a later date after the submission can then give it a QA rating.
So you have an on the surface simple report/image rating and then a more in-depth one later.
With regards to the download section, I think creating separate sections for ports, true modules, ect would be lengthy work and again could be accomplished much easier by giving each module a rating, via an image.
Sorry to go back to joomla again but maybe you have an editors pic there too:
An editor could review the module and give feedback if the grading system is too complicated.
And the compatibility issue, with images:
As a seperate issue, is the idea of having an XOOPS demo site still kicking about, whereby released modules can be demo'd along with themes. like the open source site that lets you try out all different CMS's, but geared towards XOOPS modules and themes.
I know off topic again sorry, but are we going to at some point, have all modules and themes submited to the downloads sections and source forge to ensure availability is always there.