I received my 50mm f/2 App-Lanthar from Cameraquest last week, super service by the way, (my first purchase from them). I'm using it with my A7RIV.
Fred's description and opinion are spot on.
In Lightroom, (current version) the lens profile reads "built in." Is that what other owners are seeing as well?
If one chooses Voigtlander, there are lots of choices but the 50mm f/2 App-Lanthar is not listed. I was tempted to use the one for the 65 f/2 Macro-Lanthar but did not. I looked at the Adobe website listing of supported lenses and it is not there, https://helpx.adobe.com/camera-raw/kb/supported-lenses.html.