Sorry this should probably be a seperate thread but I would second the work of separating the meter and parameters, it’s annoying that getting the number of parameters is really the number of parameters plus the number of meters, in my mind they are separate concepts.
Sorry to jump on the band-wagon but while we’re making such suggestions, I would also suggest some ability to mark a parameter as a bypass parameter. The Wrappers could check if any of the parameters are the bypass parameter and pass that one to the host as the bypass parameter rather than the wrappers always adding their own one. This is particularly useful when you are porting plugins to JUCE.
I realise this work would be a step or two on from the work being proposed here, but while your in that area of the code I think these could be some worthwhile improvements.