I am too stupid to understand where is this going.... there is seed of doubt, but now the seed is being removed... so, any hypothesis (before the official answer though)
the usual pattern is that akiyama says a bunch of stuff, then forecasts or constructs an association-with-underlying-state that isn't necessary (here: "two sus notes -> one person guilty or two people guilty trying to deflect blame") or doesn't hold up in reality so he can... ugh idk if there are good words for this. he herds the level 0 (innocent, naive, did nothing - following rules) members, level 1 members (guilty/to-be-identified - actively deceiving), and level 2+ members (those acting strategically) along splitter gates for goals/agendas/patterns of thought. in the simplest case, you can go "a guilty/innocent person would behave like this" and force even people who don't buy the association to comply. this is more ornate and elegant because the fact of attempting to communicate or coordinate is taken to be proof of traitorousness, so everything has to occur through side-channels.
here instead, the revealed equilibrium actually was: a single person uses a plausibly-deniable typographical signal that they were acting on their own. group D were watching each other somewhat. centre vs left vs exclamation mark. group C seems totally uncoordinated - normal vs. just C vs underlined. group B has weakest variance. group A is borderline and idk how it was scanlated - does Japanese have macron modifiers for characters that aren't noticeable at first glance? that's the only explanation I can think of for why "ooooo" passed under the radar.
the suggested direction this is taking is: akiyama uses the next two rounds, reassigns groups to narrow down traitors/reveal coalitions, possibly varies the group count since 12 + Nao has lots of divisors and is pleasant like that. but that seems too boring so presumably we get interesting wrinkles like usual.
I am expecting the twist to be something like that there are two or more uncoordinated groups of traitors with different agendas, and that akiyama has already guessed this + exploited it in this round somehow. that allows for fun intermediate turns like: groups try to communicate purely using these typographical signals and negotiate (akiyama slips a carefully-constructed vote in perhaps, hilarious), one member secretly defects to the other side without his side realizing, there's a lot of room here.
edit: oh, and probably the same recurring gags apply. Nao's stated role is actually useless, she's either there as a negative to more tightly herd side-channels into a place Akiyama can observe them, or she's purely a distractor meant to deceive traitors into taking Nao to be the suspicion-gate so they get sloppy. and Fukunaga is once again suspicious + holy stacked but she's just pulling her own schemes with partial knowledge of what Akiyama has in mind.