Where is Teeko located?
My Jenday, Birdie, used to be located in my bedroom. When my mother would come on the weekends to take me out to eat or shop or spend time with me, whatever, Birdie would get mad the moment she walked into my room. If she was out she would almost certainly attack. I had to put her home whenever my mother came over, and even then she'd sound off like an alarm.
After I moved, that changed immediately. My mom can handle her with no issues now. I have come up with 2 theories.
1. Birdie associated my mother, and by extension guests in general, with me leaving. This might not apply to you. But, if you think about the last few times you've had guests, did you put Teeko away and leave shortly after the guests arrived? If so, you should build in time to stand around Teeko's cage and talk with your guests. Have them give Teeko treats, if it's safe for them to do that... not if they're going to get bit, obviously. And, to borrow from a commonly suggested dog tactic, when you DO leave, always make sure Teeko has a forage toy or puzzle to keep him busy for a few minutes so he's not hyper-focused on you leaving.
2. Birdie thought my small bedroom was her room. When strangers like my mother entered the room, it was tantamount to entering her cage!! She was being cage protective but expanding the domain of her cage to the entire room, because of the size of the room.
When I moved houses, Birdie's cage was placed in the living room with all of the action, and now she sees my mother frequently and I don't leave immediately afterward anymore. It's made a huge difference. To be clear, when complete strangers come over she is still very loud. She gets excited and flock calls, and I usually won't let her out when strangers are over because when she gets really excited she sometimes bites, purely because of all of the pent up energy. But she doesn't puff up or threaten them, she doesn't get stressed out at all.