I agree that changing the name of the Agree 
button might make it more intuitive. Confirm ID makes sense to me given my language bias.
However, I think the fundamental issue you are trying to address is knowledge deficit about how the site is meant to work. No small phrase can overcome that, especially on a global site.
I looked at the idea of a pop up that would appear when pressing agree on one’s own observation. I think something like this would be helpful without being overly problematic for high volume users (because they probably aren’t agreeing with IDs on their own observations in high volumes).
As someone who clicked the Agree button too much before I knew better, I think I would have responded to this type of education (especially if it was delivered on repeat). If something like this is possible, perhaps “Just in Time” training could be inserted elsewhere into the site.
Is there a reason you left this idea out of your proposed package?