Hickory: Whatever.

UK_John: Thanks for your kind help.

Discovery103: I had the same isssue once I updated to the patch 1.12 and tried to use some mods with it. Found out solution on nexusmods in a discussion under one of those mods. Here I'm copying the post that helped me solve it:

Xanlosh 0 kudos 68 posts
This error is caused by an old Telemetykeyword.ws file you can fix this easyly by going to download the file from the misc. section and install it like a normal mod
http://www.nexusmods.com/witcher3/mods/943/?
This wont fix the issue with this mod because its not updated yet but it will fix the compilation error with 1.12 updated mods.

In case anyonew wants more precise instructions, here is what I have done and what is basically happening.

Seems like the file telemetryKeyword.ws which is located in ...\The Witcher 3 Wild Hunt\content\content0\scripts\engine was not updated for some reason (might be a problem with just the gog version, but I was not researching if for example steam version has the same issue). You can take look into the folder and in my case, every other file is updated, except for this one, which is what is causing the issues. So, what you do is:

1) go to the files section of http://www.nexusmods.com/witcher3/mods/943/?
2) download modTelemetryKeyword-1.12.zip which is in the miscellaneous section
3) unpack the mod as it is into your mods folder located in ...\The Witcher 3 Wild Hunt\Mods
4) start the game, mods should be working now

Basically what happens is that now you should have a folder named mod0000_0TelemetryKeyword in your mods folder. It contains the updated telemetryKeyword.ws and it is overriding the old file, so all the other mods that are compiled after are using the updated version (I believe they are compiled in alphabetical order, which is why there are so many 0's in the name of the folder, haven't really checked if that is absolutely the case, sounds logical). You can also just take the updated telemetryKeyword.ws and replace the old one, but I prefer this method to keep the installed files intact. Hope it helps. :)