Had a few minutes and thought I would add to the discussion.
Using consistent and accurate terminology is critical to assure a common understanding and alignment with regulatory authorities and within your organization. I have worked with clients that tend to create there own terminology and I can assure you it not only confuses regulatory authorities but creates confusion within ones quality system. For your specific question I would believe that both terms will move forward interchangeably until such time as the FDA completes the transition and training of the investigators. My suggestion is to align with 13485 / 9001 terminology right away. This allows the FDA and the remainder of regulatory authorities outside of the FDA to clearly understand your Quality System documentation.