I would never in my life put my games in an attic knowing something could crash right through the roof. But maybe they live on a ranch and never have fallen tree issues.
That said, dope set!
Oh and my source is community members but I’m sure you could find some public documentation on game boy pcbs somewhere. I didn’t look super hard though because I had great info from people directly.
I also used snescentral for the chips, which translates directly to game boy. I don’t know if they have anything about the pcb itself though, particularly for the date code module.
It should apply for other game boy games minus third party. also different manufacturers format their date codes differently.
The year is just above the pcb date squares.