I only have CS5 on this station and I suspect a reason for not getting reactions so far may be that others may not have CS installed anymore, either.
I faced some issues on using this with photoshop CS.
Have you tried wrapping it in a try-clause?
Is convertProfile available in CS?
Have you tried using the Script Listener in photoshop cs?
This is the output from the script listener for converting to the RGB
color mode without any dialog:
var id11 = charIDToTypeID( "CnvM" );
var desc4 = new ActionDescriptor();
var id12 = charIDToTypeID( "T " );
var id13 = charIDToTypeID( "RGBM" );
desc4.putClass( id12, id13 );
var id14 = charIDToTypeID( "Fltt" );
desc4.putBoolean( id14, false );
executeAction( id11, desc4, DialogModes.NO );
It works well..