B. E. B.
It sounds as though you are referring to the Medical Flight Test which in the past was conducted either by a CAA Staff Examiner or a FIE. I have done many of these over the years, in particular with disabled pilots, and if there were any specific issues, they were discussed with the CAA doctor who had initiated the requirement.
With the demise of the CAA's medical department it seems that these assessments are now put out to industry with no guidance or instructions and a rash assumnption that an Examiner will know what to do. If you are not happy to do them, then smply refuse. The CAA may then get the message that perhaps it is not a good idea to assume that Examiners who have had no previous involvement in this activity will automatically know what to do.