Hello, please do head over to the Deskthority forum for all technical questions. I can confirm with my LED testing on xwhatsit controllers (great way to add LED lock lights to an F77 or F62) over the years that I have not seen the behavior you describe. Please note that the pinout is reversed from what is in the xwhatsit manual as per the product page description:
https://www.modelfkeyboards.com/product/xwhatsit-beam-spring-or-model-f-controller/
I swapped actions inside three branchings of setLockLEDs() function inside exp.c, recompiled and everything started to work as it should. I am in grate doubt it capable to work correctly without these changes. I am not good in electronics, but I believe I made no mistakes in wiring either. The case is somewhat mysterious.