I think this really depends on whether it was an obligation on the Employer to actually respond to this report or not. The fact that it is on the accepted programme is not really so relevant. If this was a requirement within the Scope to issue this report for acceptance and they have not responded then yes it would be a compensation event as this would be a hold point. If it was not an obligation, the it would be for the Consultant to proceed in accordance with the requirements of the Scope.
If they have missed an acceptance period stated within the Scope then the Consultant can notify this as a compensation event, and any cost incurred as a result of them not responding on time would be recoverable as part of that CE quote (along with any affect on Planned Completion).