Maybe. It's hard to know what kind of issues that test suite covers. If memory safety is the main source of instability for the C implementation then the Rust implementation won't be too affected without the test suite. Same if it focus a lot on compatibility with niche embedded platforms and different OSes, which Turso won't care to lose.

"Stability" is a word that means different things for different use cases.

Coverage is described on the SQLite website