If you are more specific about what you are trying to setup I can better help you. There is currently no way to change the H90’s PC mapping. If you send PC message #1, that will load Program 1 on the H90, if you send PC #2 that will load Program 2, etc.
Is your controller connected directly to the H90? I’m not experiencing a delay like that when sending the H90 PC messages.
Parameter mapping can be achieved from the Parameters Edit menu, you can do this easily using the Learn function: https://cdn.eventideaudio.com/manuals/h90/1.1.4/content/edit-modes/parameters.html#mapping
