Just to butt in quickly: I´ve worked on issues like this in previous roles with other ticket systems. And there really is no clean solution for this, even if we extend the r3 tickets app to allow this - at least I never found a good solution.
Looking for "thank you" / "noted" / etc in responses has a very high chance of including responses that definitely do need to re-open a ticket. If somebody thanks the agent for the good work, but the issue is not resolved yet - or somebody says "Thank you for your patience" because the issue reappeared, the agent needs to know about it.
The risk of false-positives is so high, that we never found a solution and ended up closing tickets manually, when a "thank-you" response came back.
