I checked the manual and indeed says something wrong. I guess it is not up to date? anyways you already found two other ways of doing what you wanted to do.
Unfortunately that happens often, I just checked the pages 69-70, and I found something else that is not working as it is written, I guess it has been updated:
[FUNC] + [LEFT/RIGHT] to nudge tempo (when sequencer is playing).
for that, you dont need to press [FUNC] anymore.
check this for more tips and tricks.