Skill cheats work, they're just super confusing.
stats.set_skill_level major/skill_(insert skill) #
I'd recommend looking it up. Also, you pick between major or skill. That's where it's confusing because things like fitness use skill, fishing uses major, and once we get Get Together, dancing would use minor. Skills can also be called different things. For example, normal cooking would be "homestylecooking." At the # part, you just replace the # with the number you want to level up to. By the way, don't use parentheses. I just put them so it'd be less confusing.