Hi Juan Manuel Gago,
Greetings from Syncfusion Support.
We have validated your requirements and prepared a sample based on that. In the below sample, if we double click the empty cells, the custom editor window will be open and if we click the open appointment of the context menu, the default editor window will be open.
Screenshot for Q1:
Screenshot for Q2:
Kindly try the above sample and let us know if you have any concerns
Regards,
Balasubramanian S