Audio Unit wrapper with VSTPluginInstance

Hello !

I need to implement an audio unit wrapper wrapping a non-Juce VST plug-in.
My idea is to use the audio unit wrapper provided and customize it using VSTPluginInstance for the audio part (inheriting AudioProcessor) and VSTPluginWindow for the UI (inheriting AudioProcessorEditor).

I started implementing this solution. I get sound from the audio unit plugin but cannot get UI working from any host.
Thanks to AU Lab, I can choose the kind of view and in both cases, get black window (size seems right).

I am really confused with graphical library on Mac:
As far as I understood, the Juce Audio Unit Wrapper provides UI based on Carbon as well as on Cocoa.
The class maintaining the AU window is EditorCompHolder in both cases.
The EditorCompHolder object maintains a reference on a VSTPluginWindow object, itself maintaining reference onto an InnerWrapperComponent based on Carbon UI.
Can this configuration work ?
Notice that supporting 64-bit is required.

Is the solution previously described feasible ?

If it is, what could be the UI issue and solutions ?

If it is not, what other solution should I consider ?