Paul, wouldn’t “Consultant approved alternate” place the responsibility for product acceptability squarely in your lap? The definitions given for “alternate” and “equal” seem to imply that the unnamed judge of performance, intent, etc - essentially the intent of “or equal” (which never in my experience has been stated or even implied as “the same in every respect”) - is the “Consultant”.
So to me “Consultant approved alternate” reads the same as “approved equal” and is just as restrictive.