Can you add a temporary route corouted with 8/2/2023 (old habit, might not be needed with delete routes). Then delete the bad time slices routes and load the correct time slices. Then delete the temporary route, if used. You might be able to keep the events on the delete route. Then maybe change the event From/To Dates. If not, than export the event data, modify the table and append events. A few ways I would try.
Would be interesting to see what workflow/s esri would recommend to handle date issues in Pro.