It doesn’t have to read the file. It’s just adding two sections to it. Don’t ask me exactly how this is done but it’s simple. I don’t think it’s done with Exiftool. Exiftool is created to analyse how Nikon is doing it. And other brands. I think it’s in the tif specs specified. Not sure.
George
Keep dreaming, Mike.
There’s a universe between you as a user and the developers responsible for PhotoLab xx - as opposed to other raw editors which without problems open your files. I have earlier mentioned the editing limitations of PL relative to free open source alternatives. Those limitations will never go away. Set yourself free too and start your new unlimited photo life with the best raw editor available.
As an owner of PhotoLab 7 I know how often it reminds me of a dead horse. I have considered giving it away to my worst enemy, but I hesitate, it would be too cruel.
Well, if PhotoLab can’t open my files from my Leica M8.2, I will either edit the EXIF data and change it to Leica M9, or just use DarkTable.
(I used to change it to M10, but Joanna suggested M9 would be closer to what the M8 cameras have.)
Yeah, I grudgingly agree, why keep asking for something that will never happen. 
For me, this is no longer a relevant discussion for what I want to do. My answer is quite simple, open my Leica M8.2 images in DarkTable. I’ve been doing this for a week lately (and years ago), and while the software is “different”, there is no longer a problem for my camera being un-supported. I seem to be able to achieve my end results just as easily (but differently). After a week of using DarkTable, I’ve been able to achieve my image goals. Not to mention DarkTable is “open source” (free).
I have no idea what will happen when/if I start editing my infrared images in color. One recommendation was to use PhotoLab (not Lightroom). (Oops, I meant PhotoShop.)
Now, if PhotoLab allowed me to edit my EXIF data, that would open up a new world of possibilities. 
Bye bye.
George