I don't think the current conceptualisation as "Community representation" is optimal (in fact, I think it's a very bad idea but I'm trying to be politic :))
To avoid going all abstract and theoretical, let's use the internal representation as a comparison: every conceivable internal stakeholder is represented down to the individual team level (so much so that two teams actually have the same representative because sending two just wouldn't make sense). WMDE is represented by people from no less than three teams.
Is "the Community" really one monolithic stakeholder in technical decisions? Does "the Community" really have one monolithic set of priorities, interests, and skills??
Are people with +2 and at least one commit in the last 12 months really representative of "the Community"?
I would assert that this needs to be based on a stakeholder analysis (possibly just an informal ad hoc one, but it'd probably be smart to document it publicly on-wiki), to identify 1) what sensible categories and groups can the community be divided into that have somewhat coincident interests and perspectives, and 2) how can we ensure those subdivisions are represented in technical decisions.
For example, each of the sister projects will have different stakes, priorities, and perspectives: Commons will care about things affecting Upload Wizard, Multimedia in a broad sense, and structured data, where Wikipedia will have those things way down on their priorities list. Wikipedia uses templates partially to standardise their content to a house style, while Wikisource uses templates to enable flexibility and easy divergence (they reproduce external formatting and layout from paper books). Wikisource is entirely dependent on Proofread Page for their core workflow, but no other project uses it (the extension is Wikisource to a large degree). I don't know Wiktionary very well, but I do know they use MediaWiki in a completely different way from say Wikipedia (even just basic stuff like not auto-capitalising the first letter of pages).
Despite being a primarily technical person and falling into the broad category "developer", I work almost entirely on-wiki with templates, Lua modules, Gadgets, User scripts, the various sources of stylesheets, technical writing (local docs etc.), and various bots and Toolforge-hosted tools. And while I love those volunteers that have +2 and commit regularly (they certainly don't get enough credit!), I don't feel they represent my interests or perspective particularly well. In fact, the +2/commits requirement feels exclusionary and alienating to me and I hope you'll simply remove it. There are a lot of technical contributors like that who'll never have +2, but who still have a unique perspective to inform issues before the TDF.
I think at a minimum the TDF should seek to have representation covering each of the sister projects; with Commons an especially critical project. Wikidata is presumably already covered through WMDE, at least partially. I think non-English / multilingual / minority languages is a possible category, since these face unique challenges deeply affected by technical decisions (translation, i18n, RTL, Language Team / ULS; and since they are often very small communities they need efficient and off-the-shelf solutions for stuff English Wikipedia can do on its own).
And I think primarily on-wiki developers / technical contributors is an important group to have represented.
For example, so that person can raise their hand and ask questions like "It's good to upgrade our Grade A browser requirement to ES6, but ResourceLoader doesn't have lint capability for ES6 in Gadgets. How are we going to handle that?" or "These scope and requirements docs for Vue.js/Codex don't mention Gadgets and User scripts, but it's clear that this will in practice deprecate jQuery UI and OOUI in production. The migration path for this use case should definitely be covered." Not that I'm personally frustrated by the lack of ES6 support in Gadgets or a modern UI framework for Gadgets or anything. These are clearly just hypothetical examples I'm raising. For a friend. Yes, that it. I'm asking for a friend.
I think that's a much better conceptualisation of "representation" in order to get the qualifications and perspectives the forum needs. It's going to lead to a somewhat scarily long list of stakeholders from the community on paper, but 1) it's long of necessity to achieve good representation, and 2) you will definitely find single people who can represent multiple stakeholders (many of them, incidentally, among the +2s, I would guess), and not least of all 3) you will not find representatives for most of these stakeholders.
That last point is important: any fear of a flood of hairy barbarians, sorry, upstanding community members (see, I can make that joke because I'm a barbarian banging on the walls myself :)) is in practice overwrought because there are a very low number of people who actually have the skills and the time to participate (for example, I can't commit to the availability and response times required so I wouldn't be a candidate). The reality is that the biggest problem here is going to be finding suitable representatives, not that too many will flood in and turn the forum into an inefficient circus. (In fact, I would be inclined to suggest that each of the distinct sisters should have an advocate on staff at the WMF that could, among other things, represent that sister in the TDF, but that's a whole different tangent.)
Don't get me wrong, I'm very happy to see that after [insert depressingly long interval here] there is finally a real provision for community representation in some form here. But at the same time the form of that representation makes me feel excluded and doesn't make me feel like my interests and perspectives are sufficiently represented. I hope you'll rethink this and start working in the direction of better representation.