Anything that might be affected has already been affected. Draining and refilling to the proper level will have absolutely no additional affect.
The froth will disappear. Just for the record, it isn’t from pressure, it’s from aeration, just like when you whip up a batter that you’re going to cook. It affects the ability of the pump to be able to maintain a proper pressurized fluid barrier between the bearings and their respective surfaces rather than being caused by pressure. You have the cause and effect reversed. Aeration causes loss of pressure rather than pressure causing aeration.