@olivierlambert - I'm not sure who would be the best person at Vates to ping or whether there is another channel I should be using to request enhancements. I'm happy to be directed to the correct place if that's not here.
Despite the fact that I brought this upon myself... I do think that it would be nice if Xen Orchestra could improve the error handling/messaging for situations where a task fails due to an invalid object UUID. It seems like the UI is already making a simple XAPI call to lookup the name-label of the SR, which, upon failure results in the schedule where an invalid/unknown UUID is configured displaying the invalid/unknown UUID in Red text with a red triangle.