I could be nice if I could add them in Fmod studio editor.
The ability to add notes to snapshots will be included in FMOD Studio version 2.01.00.
We have no plans to support user properties for snapshots at this time, as we are not aware of any situation in which they would be useful. Is there some situation in which your game would benefit from checking the user properties of a snapshot?
I use snapshots for reverbs and with some reverbs I want to add custom tails to gunshots, so I just want mark some snapshots where I could add them.
For that purpose, it would be better to use tags. The ability to add tags to snapshots will also be included in FMOD Studio version 2.01.00.