As an example I’ll stick to my own situation.
I own a Pentax 150-450mm lens and the HD Pentax-DA AF 1.4x rear converter. The lens is supported by DxO, so optical corrections and lens sharpness are available.
The Pentax converter is one of the few that adapts the EXIF: the correct IBIS is selected, the correct focal distance is displayed and the correct resulting aperture is in the EXIF.
PhotoLab recognizes the lens, but for focal distances more than 450mm the lens correction features aren’t available. In most cases, the TC will be used to extend the range of the lens beyond the normal limit, so beyond 450mm. A focal distance of e.g. 550mm in the EXIF is a clear indication that the TC is used. But because it is out of the “normal” range of the lens, the lens corrections aren’t set. It is considered an “unknown lens”.
It would be great if PL would use the known corrections of the lens without the TC as an approximation. This will definitely be better than no corrections at all. Of course the holy grail would be to have the corrections of the combination of lens and TC, but I won’t ask for the maximum to start with 