Boris Red 4.3 library is 4:3 and not 16:9. This causes the presets to change the properties of the already established timeline from 4:3 to 16:9 every time a preset is used in a 16:9 project. Is there a workaround for this horror?
Have you tried using using the insert option instead of the overwrite option when adding the preset from the library browser? This function should "insert" or "add" the library composite to the current composite without changing the project settings.