We are converting our PM program in SAP.
In a lot of operations we refered to a standard text with a more detailed PM description.

Is there a way to see where in which PM plan we used the i.e. standard text name "PM401" with short title "PM Airfin."
(A kind of where used list for standard texts)

I don't believe that SAP has a standard report which could do this. You will probably need to write your own ABAP query or Quickviewer query. Probably interrogating the PNI logical database.