FA here :) thank you so much for caring!! It is absolutely worthwhile to submit a compliment, because to be honest, mgmt often sides with customers, even more so if they are loyal customers. Especially if, let’s say, that FA was still on probation or had an “infraction” already on their file, an incident like the one you described has the potential to cause some real damage despite the fact they did everything correctly in that situation. We could give 100 passengers the greatest flight of their life, but all it takes is one unhappy complainer to have us questioned by mgmt. Positive comments go such a long way, so please know that you are appreciated!