Soccer “Senior Official” question

I’ve gotten back into reffing soccer for this season. Due to a lack of refs I did 2 JV games with a ref who has 10 plus year of experience(his words) and would take on the “Senior” official role. He was very difficult to work with and I’m not sure what to do about it. During the first game we had a quick talk about letting the teams play and try to stay away from the ticky tack calls. 10 minutes into the second half he pulls a yellow card on a player for extending their arms.. it wasn’t a push and the type of play happened a bunch of times.. I was on the coaches sideline and both coaches asked separately what happened as the play occurred on the opposite side of the field. I really had no answer. The second play is the bigger issue as the other ref called a hand ball on a player he couldn’t see and I couldn’t see clearly. After the game I asked about it and he said it had to be a hand ball by the way it came off the player and proceeded to tell me as I get more experience I’ll learn to make calls like that.. Sorry for the long post but is he correct? Do other soccer refs make calls on what he think happened rather than seeing it? And are you better off using a yellow card early to keep a game from getting chippy that really never got bad?