>stab trim 2 is an informational message -( there is a good write-up about use of the non-normal QRH in Checklist Introduction, Boeing QRH). A careted message requires no reference to the QRH as "the crew's action is obvious". It may well be transient, it certainly requires close monitoring and as a preference I would disengage R autopilot and engage either L or C autopilot.
The logic behind EICAS warnings and messages (including 'status messages') requires a thorough understanding, but don't try to "out-think" Boeing, as the a/c has now been in service over 20 years. Actions in the event of a malfunction, have been designed to simplify the operation, as much as possible, as there is no longer the 'luxury' of a Flight Engineer's knowledge.
