Thank you for your interest in Syncfusion products.
Based on the provided information your requirement of triggering AppointmentEditor through button click can be achieved by ScheduleCommands in SfSchedule WinRT. Please find the below code example,
We have prepared simple sample based on your requirement, please find the sample below,
Sample link: ScheduleSample_WinRT
You can also refer our online User Guide documentation for ScheduleCommands by the following link,
UG link: https://help.syncfusion.com/winrt/sfschedule/commands
Please let us know if you have any further query on this.
Subburaj Pandian V.