I want to flag processes with problems to have an easy overview. Is there a possibility to flag processes in the Explorer like they are flagged when there is a new comment?
It is not possible to flag a process like its flagged when there is a new comment.
What you could do is to create an attribute on diagram level of type boolean. This will create a checkbox. Then go to setup and "Edit general configuration". Add this attribute as a column for the explorer.
The result could look like the example in the screenshot below.
KBA , BPI-SIG-PM-EXP , Explorer for SAP Signavio Process Manager , How To