Please give me your clarification of a rule about calling a LET (on the court next to the court you are playing on) when a ball is accidentally rolling onto their court. I always understood that ONLY the four people on the court, where the errant ball is still moving, can call a LET on their own court. Not the people in the adjacent court who hit the ball there as it may not always interfere with the point that is in progress.
Case in point:
A tennis friend of mine will always immediately call an errant ball that is going onto the adjacent court. She was injured years ago when no one called a LET, she stepped on the ball and severely damaged her ankle. She is adamant about calling a LET.
So, if I am playing on court 1 and I see a ball going dangerously towards court 2 should I say something? Again, no, especially if it is a tournament or league match. However, if this is a friendly match or social tennis then I would say absolutely for everyone’s safety warn the other court and player(s) that there is impending danger. I do this all the time when I see players practicing and a stray ball is heading their way.
The answer to your question is “yes.” The right thing to do is absolutely try to assist and prevent a potential problem, but it depends on the circumstances. If it is a tournament of any kind, you should not interfere with another court as it is the players on that courts responsibility to stop play and make a let call. I have also often seen players continue to play even when a ball traveled onto their court, because it did not interfere (in their opinion) with the point being played. Bottom line you have to leave it to the discretion of the players on the court where the let could potentially come in to play.