A friend of mine told me today that he upgraded his Steinberg Artist for WIndows from V11 to V12 and now he can no longer host NI Maschine as a Plugin since it's VST 2.4 but Cubase now exclusively uses VST 3 only on PC.
So I am wondering if you can host NI Maschine VST 2.4 via Unify in Cubase 12?
Your friend is wrong. VST 2 still works in Cubase 12 in Windows and Mac except on Silicon in native mode. With Rosetta, it's ok.
Win 10 and 11/Cubase Pro 12/Unify/Wavelab 8/Vienna Pro 7/Spectrasonics all/NI 13 Ultimate/Izotope MPS2/Serum/Cthulhu/Scaler 2.5/MusicLab guitar vsts/BIAB 2022/TouchOSC/Metagrid Pro etc
Unify should have no problem hosting VST2.x plug-ins. You will probably need to use the VST3 version of Unify in Cubase. We have had reports of some issues with the VST3 Unify plug-in. I'm working on updating Unify to the latest version of the JUCE framework, which I hope will improve the situation.