QC

The version of Buddhism he seems to be drawing on is roughly the Daniel Ingram version, which is a severalth-order derivative of the Mahasi version, which is a severalth-order derivative of 1800s Theravada.

This doesn’t make it not-Buddhism, but it does make it not at all The One Correct Buddhism. It’s a quite extreme outlier among Buddhisms.

It’s also one that I, personally, don’t care for. It seems to work for many people, up to a point at least. But it’s important to recognize that it is only one approach among many, and that other versions are very different, and may work better for at least some people.

It would be nice to have a collection of different versions steelmanned in similar colloquial language

Well, each does have its advocates, who do present it in reasonably contemporary English

I guess what’s generally missing is clear comparisons. That’s difficult because few people have practiced disparate systems deeply enough. And actually few people even understand their own systems clearly enough to explain their fundamental principles.

This makes me think the distinctions might need to be presented as dialogues. So you could present a similar core engine of Dzogchen (if that's a meaningful notion) and then you & Romeo could ask each other clarifying questions: "Ahh, so does that step involve...?" etc