Thanks for your time and effort to explain how to proceed. Much appreciated.
This was actually the first time I've seen a black PCB in person and the first thing I've noticed was that traces are barely visible. It's really annoying.
On to the troubleshooting. Honestly don't know enough about electronics/PCB so I didn't dare go beyond first step because it produced different results to what you said it should. BTW, if shorting all other combinations would be safe to do I can check them anyway - unless there's no point since the orange+cyan produced different results. Sorry, I'm a noob, first time doing this. Generally speaking can I short two wrong points and actually damage the PCB?
Shorting the yellow to the cyan typed the whole row with slightly varying results. I was scared of pressing too hard and for too long so it might have been me doing a bad job when testing. Is it safe to connect them for longer (let's say a second or two)?
Switch hitter results (I forgot to change to 88 key ISO but I presume that just changes the layout nothing else):
I've opened the notepad while shorting the yellow and the cyan a couple of times in a row and this is what I got (each line is it's own shorting):
^1234567890ß´
8^1234567890ß
^1234567890ß
^1234567890ßOnly the first sequence is complete and correct but the results not being the same each time might have been me shaking and pressing too lightly or backspace, insert, home, page up all getting triggered as well since they're in the same row. If it's ok, I can try again and just press firmly for a second if necessary?