Thanks for the input, Mattylad, it led me to a workaround.
I don't know how to create parts in the library - I cant find out how to do this (or edit them)
When you create a part (as explained in the video tutorial), there's a step at the end where you choose the library in which the part will be created.
There also is a step where you can add the fields you want to the part.
So the workaround would be :
1. Create a part in the "new parts" library, and add a property "status=new"
2. When the part has been doubled check by a second person, this person :
2.a. Changes the property to "status=checked"
2.b. moves the part from "new parts" library to "checked parts" library (through the library mode)
3. When the circuit actually runs and the new part is mistake-proof
3.a. Change the property to "status=proven"
3.b. moves the part from "checked parts" library to "proven parts" library (through the library mode)
Now, I just need to display the "status" property in the BOM in order to see where my circuit needs double-check.
That's rather heavy, but it seems to do the job.