What happens if the training flight was actually three flights
You need to re read the regulation.
ALL of the revalidation requirements need to be met before the licence can be signed. That means if it's split over more than one flight it is signed after the final flight that completes the requirements.......
Now I refer you back to my comment about the differences between examiners and authorising an Instructor to do a limited Licencing action on behalf of the authority......