You may simply ask when they state their testing indicated good...exactly what is tested and how?
A simple resistive load and a voltmeter that is not closely watched may not indicate what is happening
You remind them that something that the generator is outputting is causing the ac to draw substantial current resulting in the breaker tripping.
Contact the manufacturer of the ac units and talk to a tech support person and send them the link to this thread and ask for their advice as well.
Ask them if your units could have been damaged by this or what specifically to look for.
Tony & Lori
1989 Country Coach Savannah SE