Maybe these will help?
How to Use Tempo Warp in Cubase | Q&A with Greg Ondo - YouTube Creates a click track from the freely recorded performance, then stretch the whole song … the song will get sped up/slowed down.
Changing the Tempo of Audio in Cubase - YouTube . Though he didn’t mention, I think the MIDI tracks need to be in Musical Time Base … but not sure, would have to try it to be sure.
Tempo Editing in Cubase - YouTube . This one is to “create a tempo map” , to create a click track for the drummer, or if you wanted to add a MIDI-based VST instrument (like VST Drums, etc.), or making external loops follow the track tempo. But even if that’s not what you need to do it’s pretty cool, and it supports and reinforces the first vid well
Cubase Fix - Change Project Tempo without Moving Parts - YouTube He says “Mode” but that’s incorrect, it’s “Time Base”. "Remember, a good rule of thumb is: when changing to Linear Time Base, the start of the part/clip will remain at the same min:sec value, but its starting bar:beat value may change.
Conversely, when changing to Musical Time Base, the start of the part/clip will remain at the same bar:beat value, but its starting min:sec value may change."
(Btw,there’s a Project Logical Editor setting for one-click setting all of the tracks to Linear vs Musical Time Base).
Check out this thread too, it reinforces some of the above, and may have another tip or two somewhere in there: changing tempo moves events in musical mode - Cubase - Steinberg Forums