A mexicano is a club night where each round is dealt off the table as it stands. Everything else is an americano: you get a new partner every round, you score the points your side won, and the highest total at the end wins the night.
How a round is dealt
The first round is dealt like any other. After that the table decides: the top four share a court, first and third against second and fourth, then the next four take the next court, and so on down. So a good round moves you up the room and a bad one moves you down.
What that buys is an evening that tightens. By round five you are playing people who have scored what you have scored. That is the thing a club night usually cannot arrange, and it is why clubs run this rather than an americano.
What it means for you
You are never out of it. You score points rather than matches, so a bad round costs you the points in that round and nothing else. The next one puts you in with people on your own score, where the games are closer.
The rounds are dealt one at a time, not all at once, which is why the standings have to be up to date before the next one goes out. Your organiser puts the scores in and presses deal.
A correction later on
If a score turns out to be wrong it can be fixed, and fixing it changes the table without changing any round already played. The courts you were put on were dealt off the table as it stood at the time. That is left exactly as it was, because the evening happened the way it happened.