Yes, it’s a very tough choice of what one can effectively do.
In my limited experience, even a “respectfully” written note of advice or criticism by non-members to a pulpit rav (yes, I know I’m generalizing here) will rarely lead to change.
As some – including the original poster – have already noted, the rav is likely aware of the problem and either hasn’t succeeded in changing things or doesn’t consider it his top priority.
In an meager attempt to be “dan le’kav zchus” for that rav, regarding priorities, I suggest that it’s possible that the congregants have even more serious observance issues, r”l, that the rav feels need to be addressed before he weighs in on decorum.