I just wanted to report (as I'm certain Canvas/instructure is already aware).
I taught a course in Fall. It's a fall course that I don't typically teach in spring. I copied the course from last year. I told Canvas to adjust dates and gave it the start date of the new semester I was coping to. I expected to do some manual adjustments to the due dates--either by lock times, time due by, or lock after dates. However, copying a course to one year later wrecks havoc with the due dates/times. Something due in August last year, should at least result in due in August of this year--not June. Something due in December of last year should at least wind up in December of this year--not January (2 months) later. Same goes for the lock dates/ unlock dates. Even if the due date changes, the unlock/lock after dates don't transfer the same way. Many keep the old year resulting in something that unlocks/locks a year before it is due. I expect to do some minor tweaking if needed, but I always hope that it would at least transfer to roughly the same time relation as the start date change to.
Again, I'm certain somewhere on this site, Canvas is aware of the difficulties with this. Therefore, I am assuming that it is being worked on (at least sooner or later).