Okay, I think what is happening: secure-scuttlebutt depends on level-sublevel, and log db is actually part of the main ssb db, https://github.com/ssbc/secure-scuttlebutt/blob/6dde1c5e1d32a7427848bfad8a4641577bd0d1ab/index.js#L91-L109
since you disabled ranges, it's breaking this and you've just read past the range that logDB is located in, into the rest of the database - where the keys are hashes and the values are objects.

That seem like an exact diagnosis of my problem. I guess I just need to carefully implement ranges and lexicographic comparison of UInt8Arrays (maybe a naive key.toString('hex') would work).