[Swiss1000]

I have the same "problem". What I do, when arriving home after a gig  is simply clicking on the songs tab a and then, sort by date modified.
Your modified songs will be at the top of the list. 
Another easy workaround would be to add the songs you modify to a custom collection ("ex, "Modified songs"), so you can easily find them later.

Your solution not really works :

• 1) You have anotated files (sheets) and they appear as you said, in first position by modification date.
  
• 2) You proceed to the definitve modification, but the sheets stay in first position (because modification date)
  
• 3) Wordst : you proceed to fix another, and it move up, after 3 sheets you are lost...
  

A field "Contain annotation" avoid this, after correction, if you remove annotations, the field is reseted.  
Another solution could be a counter of annotations. When the counter is 0, it is like a reset.
Of course, from experience, I suggest opening the "edit" process to refresh the counter, or live, because sometimes the counter could be out of step