It would be very handy if I could specify “global” custom parameters that are applied to all instances on export.
In my current project, that would be “Scale to UPM” and “blueScale”, which are identical in all instances. I imagine there must be lots of cases where one wants the same custom parameter applied to all instances.
Defining them globally would make things easier to maintain, more convenient and helps avoiding mistakes (i.e. forgetting to update the custom parameter in all instances).