I am an independent advisor investigating your inquiry. At this time, the Reschedule title in the confirmation message is not available.
I encourage you to influence change by adding your requirement to the Microsoft Bookings Feedback portal or Microsoft Bookings Ideas Forum. Both places will allow others to vote on your request. And, you can vote on others too.
See what others are requesting for Bookings Rescheduling.
If you find this information helpful, please mark it as the best answer or like it, which will assist others with the same question.
Have a good day.