If voice review depends on one person's intuition, start by preserving one representative example. It gives the investigation a concrete reference and makes the eventual correction easier to judge.
Find the likely cause
The guide lacks observable criteria.
Treat this as an explanation to verify against the actual work. Look at the input, the relevant decision, and the final result together. If the evidence does not support this diagnosis, investigate the mismatch before applying a convenient but unrelated fix.
Make the targeted correction
Define checks for jargon, sentence structure, claims, and preferred forms of address.
A useful voice guide describes repeatable writing choices with examples rather than relying on abstract personality adjectives.
Check that the repair worked
Have multiple reviewers apply the same checklist to one draft.
Repeat the check on the final version that the reader or customer will encounter. An approved draft, a preview, and a published result can differ; the acceptance decision should concern the version people actually use.
Prevent the next related failure
A separate issue to watch for is this: aI brand copy sounds polished but unlike the company. Provide approved examples and explain their specific writing choices.
Monitor the useful outcome
Track voice-related revision effort and consistency across contributors and channels.
Keep a short record of the original symptom, the evidence behind the diagnosis, and the result of the acceptance check. That record makes the solution reusable when the same condition appears again, without assuming that every superficially similar problem has the same cause.