No, it is not the referee's job to know the behavior of the cueball. Never has been and never will be. You do need to see contact - because which ball was actually hit first is what the judgement should be based on according to the rules of the game. You can't make decisions on "ball behavior" because then you'd be making judgements about situations way more complex than this based on what "probably" or "everybody knows" happened.There is no tech needed on many shots, and it is referees job know the behavior of cueball on foul shots IF he want to be good referee, as Marcel probably wants. That 4 ball shot cueball can go forward but the speed that cueball have after hit is clear evidence of foul. Slow speed on shot and cueball have lot of speed and going to left tells there is 2 thin hits on balls, If it would hit 4 first cueball would not have much speed left. very simple. No need tech we all know that is foul instantly. You don´t need to see contact, ball behavior is enough.
edit: and every good player know that is foul instantly. Capito was just capitalizing dumb referee mistake..