Kobo dates are when the book was last accessed. Since everything was NEW on that device... Recent (is a reading status) follows.
That does not change Calibre's basic metadata (reading stats are Custom columns if used)
I have done a backyard semi-sync when I switched which readers I want to read
that book on (My Libra stays home. The Aura travels
. Mostly, I just read the books on the device they are on)
Backyard-sync:
Look at each book on the old (in reverse order: bottom up Remember what you did first and stop), Goto the same place on the new.
Repeat as needed. Only the dates read are different. The order and place is maintained
Kobo Utilities can RESTORE stored (in Calibre?) reading positions.
I have both PI installed, but the extended edition disables KU when being used (you can switch on the utilities icon)