Even though she is a bit shy, it's better to have them in a central location where they can still be with their "flock" even if they're in the their cage.
My galah is in our living room, which is the most active place- but it is also open to the dining room and kitchen (they're all one big open room). Her cage is in the opposite corner from the kitchen- as long as you're using bird-safe cookware and using good ventilation if need be, it's fine. I always put Chili in her cage though when I'm cooking to prevent any accidents if she were to fly into the kitchen.
I tried putting Chili in a bedroom during the day, but that didn't work out so well- she did not like it one bit [emoji51] but! being in the middle of everything is what she's used to.