I completely agree with those finding it annoying and open an issue for adding a read-only mode to openmw-CS some time ago.
That would be helpful if implemented, agreed, but that doesn't remedy the issue. I research other mods in a similar fashion as stated in your provided link but if I interact with any script fields, I exit without saving, a.k.a., 'Discard Changes', to dodge the modified tag. My issue is with the mods I'm working on. I don't do it anymore, much, but before I began noticing it, I would copy vanilla script portions and save sometime thereafter, thusly creating modified records.
Which brings me back to one of my original questions: Is my mod now dirty if saved after an unintentional modification? Or, perhaps a more apt question: Why are script records considered modified when they were only copied? I've noticed it happen when an object's x, y or z coordinates are copied as well. The little star that signifies an edit will appear in the title bar.
I guess I'm trying to understand the mechanics underneath the process.