The WaveLab 9 installers for Windows exclusively install the corresponding 32-bit or 64-bit architecture exchange component, even though this component is loaded by Cubase 8.5.x.

Accordingly a Windows 64-bit installer only installs the 64-bit WaveLab 9 exchange component, and a Windows 32-bit installer only installs the 32-bit WaveLab 9 exchange component.

Therefore it it not possible to access Cubase 8.5.1x/32-bit from WaveLab 9/64-bit  and Cubase 8.5.1x / 64-bit from WaveLab 9/32-bit.