An independent senior architect or advisor who is not responsible for selling or implementing the proposed solution can review whether the architecture is coherent, complete, aligned with business intent and operable in practice. The review should test assumptions, dependencies, ownership, integration, transition and consequences — not merely whether the diagrams follow an architecture notation.
What should be reviewed?
Business purpose and constraints; target and transition architecture; application and integration impacts; data and ownership; operational model; security and non-functional requirements; vendor dependencies; delivery sequencing and decision gaps.
Why independence matters
A builder can review quality, but has incentives and assumptions tied to the chosen solution. An independent reviewer can ask whether the problem has been framed correctly and whether another arrangement would reduce complexity or risk.
Useful output
A short written opinion: what is sound, what is missing, the risks that matter, questions that must be answered and conditions for approval.
How soapplied approaches the question
I would not start by assuming the stated problem is the whole problem. The first step is to understand the people, purpose, constraints and interactions around it, then test what intervention would improve the system rather than merely optimise one component.