the buttons get oxidized over time not being used regularly. with the vehicle off just mash on the button till you get tired. maybe all the pushing cleans them up enough to be useful. or replace the buttons.

 

Concur with Bronx - WITH ENGINE/IGNITION OFF - try spraying some electrical contact cleaner around the steering wheel buttons and sit there pushing/releasing them a lot. Had an issue with my volume buttons triggering the channel change. Actually used some WD40 (just a bit) and exercised them. Worked out just fine. The contacts & switches do go bad. Luckily the switches are still available and cheap on Amazon/Ebay Motors.

WRT the cut WSS wire(s), while that could be the cause of your 4WD issue, I'm surprised it isn't throwing a warning light at the dash. Or it may be a cluster issue which explains the language and no error light/DIC Warning.
BTW - headlights wouldn't be on during the daytime unless: you were in a semi dark garage then the dash sensor would turn them on, the HL switch was on rather than norma Auto position, or a PO has made some DRL/Headlight re-wiring. A lot of folks like to change the way the DRLs and/or HLs work. Good luck with all, and keep us posted as you progress. Everyone is here to help.

 

Button switch contacts get filled with dust/debris. Try compressed air to blow it out or take apart and clean with CRC® QD® Electronic Cleaner