This isn't an inherent property of ZFS at all. I have made heavy use of SQLite for years (on illumos systems) without ever hitting this, and I would never counsel anybody to disable sync writes: it absolutely can lead to data loss under some conditions and is not safe to do unless you understand what it means.

What you're describing sounds like a bug specific to whichever OS you're using that has a port of ZFS.

I wouldn't recommend SQLite on ZFS (or in general for other reasons), for the precise reason that it either lags or is unsafe.

I've encountered this bug both on illumos, specifically OpenIndiana, and Linux (Arch Linux).