Often discussion with an umpire is the only way a coach will identify this problem. It may be caused by a number of factors, any or all of the above for example. Once again knowledge and experience will overcome this problem. It is very easy to present umpires with a long list of things they have done wrong during a game. Good coaching ensures the umpire gets the knowledge he needs to improve.
Most umpires can only handle changing one or at most two things in their umpiring at a time.
By all means make notes but don't expose umpires to all you have written, expose them to the things they most need to and are able to change in their next game. Prioritising the problems in an efficient way is the mark of a good coach. Prioritising means taking into account the ability of the umpire to handle change, the things that are most urgent and those that are easiest fixed. Coaches should be wary of coaching or even talking to an umpire at halftime. It can give wrong signals to both umpires and players.