I'd say pretty accurate:

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English verbal paradigm is rather barebones; because of that, the content verb of a sentence often "ditches" meaningful distinctions into the rest of the sentence. Sometimes an aux verb, or even a conjunction. That's the case here; you got a distinction between realis and irrealis, that plenty languages would convey through the verb, but English doesn't.

Note the "counterfactual timeline" (irrealis past, unreal time etc.) often deals with events the speaker wishes that would have happened in the past.

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Ah, here's a paper about this. I didn't read the paper fully, but: apparently it is computable but NP-hard.

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Indo-European. Germanic branch.

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There's a proposed language family called Dené-Yeniseian; the languages in question are spoken in Siberia (Yeniseian) and a chunk of North America (Na-Dené).

Trivia: remember the Huns? Likely Yeniseian speakers.

schwa

The current mainstream hypothesis is unvoiced vs. voiced vs. breathy voiced. There's also a bunch of alt hypotheses including glottalisation; for example "stiff" unvoiced (i.e. [p t k]) vs. pre-glottalised vs. "slack" voiced; Javanese has the stiff/slack contrast, and pre-glottalised consonants are somewhat common.

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Two main pressures:

• the speaker wants things to be easy to pronounce; e.g. if an articulatory gesture is unneeded, it might get ditched.
• the hearer wants things to be easy to distinguish; e.g. if two sounds associated with different phonemes are a bit too similar, and the distinction is meaningful, they might drift apart from each other.

Those two pressures are in a tug-o-war, and that tug-o-war drives sound changes.

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I feel like the spread of Afro-Asiatic might have to do with this period, as it probably allowed people to migrate further than through drier periods. But past that? I have no idea, and I hate that I have no idea.

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Eh... it's complicated. It seems, for most authors, that Tibetan and the Sinitic languages are in different branches of the family; and usually Burmese is placed in Tibetan's branch. Everything else, though? No consensus at all.

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The problem starts with the definition of a language. I'll illustrate it with the Romance languages:

• If you speak Portuguese you'll probably understand Galician just fine. So let's count them as a single language. It's reasonable, right? Portuguese is basically a Galician dialect.
• If you speak Galician you'll probably understand Asturian just fine. It makes sense - both originated from Latin dialects spoken right next door to each other. Let's count both as the same language. Alongside Portuguese, as per the step above.
• Asturian and Castilian/Spanish are really similar, so let's lump them together. Alongside Portuguese and Galician.
• Castilian and Aragonese, too. Same language as Portuguese, Galician, Asturian.
• Catalan is really similar to Aragonese. One more into the bag!
• [one thousand steps later...]
• Sicilian and Calabrian are really similar, right? Same language then. They get into the same bag as the others.

So you reach the conclusion that none of those varieties "counts" as a language. Then you proudly put in some paper "number of Romance languages: three (Italo-Western, Sicilian, Romanian). Italian is now an Italo-Western dialect, French is an Italo-Western dialect, everything else is a dialect.

Except that most of those so-called "Italo-Western speakers" can't understand each other. And the speakers don't consider their native varieties the same language, they consider it as different things.

But this isn't just with the Romance languages. Cue to English and Scots, or the Germanic varieties in the continent. Or the Sinitic varieties spoken in China. The Bantu family. The Slavic branch. I think Quichua has the same issue, too.

Yeah, nah, you aren't "counting" them - you're placing arbitrary divisions here and there to make the number bigger or smaller.