If you are using the cheat to hide the plumbobs over your sims this also removes the ability to modify lights in game. Is this what you are talking about? If so use the cheat
headlineefects off and light functionality will return.
If this isn't your issue then maybe you are experiencing something along the lines of this reported bug. (Scroll down the post for more recent lighting issues)
Lighting Bug ReportThe glitch you are experiencing is more likely due to using cheats as the devs have warned us to be careful using them as they can and do cause game issues, rather than anything to do with the alien baby.
The easiest way to test your game without your mods etc is to just simply move them all to a folder on your desk top. Then fire up your game, test the lights etc then
quit without saving. That way when you put your mods etc back in your saved games will be exactly as you last played them with all the cc in place etc. It doesn't take long to do and might help pinpoint the problem.
Least that way you'll know for sure that it is not your mods/cc as if the lighting glitch continues in an unmmoded game then it most probably is a game fault/bug.
Remember to delete the localthumbcache.package file after removing your mods folder. (I do this after every play session as it helps to keep the game glitch free a little. So it won't harm or alter your saves.)
With the cooking gourmet glitch: does your sim skills panel show that she has level 10 gourmet cooking? Or just level 10 ordinary cooking?