Not really. The 'R' examiner requirement is for authorisation to conduct revalidation 'by experience' sign-offs and provides the CAA with adequate assurance that the examiner understands the associated requirements....
Thus if a Microlight FE is not qualified to fly SSEA / SLMG aircraft, authority to include sign-off approval for SSEA / SLMG revalidation can be achieved by applying for 'R' examiner authorisation.
BMAA should be able to advise further.