Technically, an international ticket does not entitle you to free same-day standby or same day confirmed change, so if you get home earlier than planned, consider that a blessing. On an international ticket, passengers are always permitted to make a change on the return trip but I'd be worried about the add/collect amount, especially in the OP's circumstances.

That said, I'm usually successful in standing by for an earlier domestic connecting flight in the OP's situation. Depends on the agent.

On a wholly domestic ticket, I'm entitled to free same-day standby, and I push back when agents don't want to add me to the list.

On an international ticket, I'm not entitled to anything other than my ticketed flights, so I meekly ask the agent if there's any chance of getting on that earlier flight. Usually, I'm successful.

Contact AA about a few EQP? Seriously? As someone else said, the double bonus EQP promo excludes "mistake fares," so I'd be thankful that AA honored the fare and awarded normal miles and points.