is there a way I can "cut" to the clipboard the content of this variation, change the tempo to a double-time feel, and "paste" what's on the clipboard?
Sadly, no.
What follows here is really waffle but I am just trying to explain how I see this problem and help you understand that the change is not easy.....
A style is recorded and built in a constant tempo (through
all style elements) - I do not know of a way to modify the time signature (i.e. double time) of a MIDI piece, which is what the style elements are. There may be a PC MIDI sequencer which can convert the time signature and hence "double" the time. If you exported all the VAR 4 parts and Chord Variation parts to external MIDI sequencer (for example, let's assume it is 4 measures long) you would need to convert the 4 measures (as they are) to just 2 measures without changing any MIDI notes. Effectively you have now got the same 4 measures into 2 measures. Now on the PA1XPro, you would have to clear the VAR 4,make it only 2 measures in length, and import the external converted MIDI.
You would need to do this for all ACCs, DRUMs, PERC, BASS for every CV (Chord Variation) in VAR 4 - a lot of work!!
Personally, I wouldn't even commence trying this - I think I could re-record VAR 4 in half the time (if you'll pardon the puns

)
BTW I found this feature important through the use of "cha-cha" in my old i3
Not sure I understand that statement but if you achieved this on your i3 than you should be able to do the same on the PA1XPro, however I would be very interested to know how you did it.
Out of interest, which style are you wanting to change?
Don't know what else to suggest.... sorry...
Good luck
Pete
