Most significantly, it's strange for the person writing the design doc not to be the person implementing the code. This is asking for trouble because there's a principal-agent problem[0], and also there's bound to be signal lost in the handoff between designer and implementer. It's not so unusual for the design doc author to work with a team on implementation, but they'd still be actively involved in implementation, which sounds different from what you're describing.
I've also never heard of this separation between a conceptual design doc and a logical design doc. I've been on teams where the product manager writes a UX-focused spec, and then the dev writes a technical-focused spec, but I've never heard of a conceptual vs. logical spec.
Does the org have a strong engineering culture in other ways? Like automated tests, automated deploys, automated monitoring/alerting, useful code reviews? Because the easiest answer is that you're in an org with poor software engineering practices, or at least weak documentation culture, and the design review process you're experiencing is there for historical or political reasons rather than engineering reasons.
[0] https://en.wikipedia.org/wiki/Principal%E2%80%93agent_proble...