AA dom-to-int connections do not require this terminal change. Since there is no immigration or customs on departure from the US, AA flights depart from T3 (flights arrive at T5 to let off passengers and then the plane is moved to T3).

Still, your connection should be no problem if the incoming flight is not late. The inter-terminal train at ORD is a retrofit so it requires various up and down escalator rides. But the train runs frequently and takes only a few minutes. 20 min after exiting the incoming flight, you should be in the T5 security line, but allow 30 min. Walking to T5 is impractical.