Now I feel silliest. Today I had time to get at it again after some time, and while I was trying to think about it I realized it's just a simple click button. In other words, all controller boards have the exact same button and thus the exact same valued resistor. Only some others are physically bigger.
I was overthinking it because maybe different CPUs could've required different values and all that. I simply took a resistor from a donor board, a JDM-055, because the kit I bought from Aliexpress had only one physical size for all and they were too big. The one from the JDM-055 was also bigger, but I grinded the ground point a little bit and made some space for the bigger resistor to connect to both points.
Thanks for the reply, RDC.
I think I also understood today that, unlike capacitors, resistors apparently can be read on-board and get a good reading. I need a fume extractor. I'll be buying one soon.