Hello,
yes these limitations still apply and I advise you to be very cautious with the results given by the diffraction module.
The only new feature of the version 6.3 concerning the diffraction module is that you now can choose the OPTION FOR SECOND DERIVATIVES (Default value : 1). The second derivatives in the formulas involved may be computed by the Freemesh method(option 1, accurate but expensive), or more simply with two successive derivatives in finite elements (option 2, fast but with some noise in the results).
Regards,
Elodie