Did they pass all unit tests in the end ?

If it works, then it’s impressive. Does it work? Looking at test.sh, the oracle tests (the ones compared against SQLite) seem to consist in their entity of three trivial SELECT statements. SQLite has tens of thousands of tests; it should be possible to port some of those over to get a better idea of how functional this codebase is.

This blog post doesn't say anything about your experience.

How well does the resulting code perform? What are the trade-offs/limitations/benefits compared to SQLite? What problems does it solve?

Why did you use this process? this mixture of models? Why is this a good setup?