I did my update directly from Mojave 10.14.6 Supplemental Update 2 two days ago. Upgrade was successful, but not as smooth as I hoped. I updated Clover from r4961 to r5070. I updated the kexts and added SSDT-ECUSBX.aml in Clover/ACPI/patched folder to resolve the apfs module start error. At first boot to Catalina, bluetooth was not available, so I added BrcmBluetoothInjector.kext in addition to BrcmFirmwareData.kext and BrcmPatchRAM2.kext in my Library/Extensions folder. Other than these two minor issues, everything else work so far.