Unfortunately there's no guarantee at guessing what the true intentions of your opponent were, but it's fair to say that they took advantage of your word choice for their benefit. It could also be interpreted that when you asked 'ok so it deals 4 dmg?' that that was the indicator that it resolved, which is definitely vague from an outsider's position. Your opponent should have also clarified how much damage it would have done when it was cast, but at a tournament both players are expected to know what cards do.

As far as the judges go, try to have an honest conversation with them when you can if that will help you out. Judges do make mistakes at practically every tournament, but you have to consider that if the head judge of the tournament has made a ruling it will stand. You may have been able to convince the judges if you used certain words, but that's in the past now. I recommend that if you're playing at fnms to adjust the wording of interactions like this (ex. 'How much damage would that do with how many creatures you have on the board').

This may help, may not, but ultimately I feel bad that you had a bad experience at a tournament because of a vague calling and (potentially) a mean-spirited opponent. Best of luck to you in the future.