If the garage GFCI trips the kitchen GFCI there's a problem with the wiring.Kitchen countertop circuits aren't allowed to come from the garage, or go from the kitchen to the garage. If there were a failure to trip I'd comment that the GFCIs manufactured before 2003 have a high failure rate, approx. 50%. I suspect a miswired multi-wire branch circuit, or an outlet extended from the kitchen to the garage is the issue, but it'll take an electrical contractor to sort it out.
