Hi,
I think it's a misunderstanding. When using Corona, 3ds Max handles the file outputs at the moment. You cannot just set properties of another engine, they do not exist. However, you can access the frame buffer data like this and do anything in a script with it:
-- for all engines:
render1=getlastrenderedimage()
display render1
-- Corona VFB access. 0 is channel beauty, the booleans mean postprocessing and renderstamp included yes/no:
render2=CoronaRenderer.CoronaFP.getVFBContent 0 true true
display render2
Usually you can find that information here:
https://wiki.corona-renderer.com/maxscriptBut for some unknown reason it's down atm.
Good Luck