Rhemic Empire (2)

Basically, you have a speed of 10 with a scout carrying a rifle, so you won't need to switch weapons. You'll have good range, one-shot kills from stealth, and a good chance of not losing stealth.

I think if anyone tries to get in, they'll attack directly in the hall. They'll find a way to avoid being searched. Or they'll break through the ceiling and descend on ropes, lol. What's the point of me standing in the corridor then, and then running into the hall?

Well, that's the dilemma. If we assume that the enemies will only come through the entrances, then the point of placing you near the corridor is that if enemies appear, you can shoot them down like in a shooting range while we three take them down, and that would be very effective. In this case, only the archer will be picking his nose in the hall on the balcony.
And in the worst case, we'll retreat through the center, and you'll also fire once and immediately run through C, and meet us and our pursuers with fire.

But if they actually spawn in the hall, then the archer will fire a couple of times at them while we all return to the hall like idiots for one or two turns.
I doubt they'll break in through the ceiling with a helicopter, and as for smuggling items in, it's theoretically possible if there's some idiot among them.

a place for a thorough search of each visitor, with the exception of high-ranking persons – the king, his retinue, and, of course, Ipomea Flox.

Well, logically, that shouldn't happen, but in the Revan world, who knows. There might be some overly zealous kings or queens who are suicidal. Although, not searching the retinue is harsh.
However, if the king or his sister get stuck in the room with Ipomea for some reason, we'll probably not be able to save her...

Well, if you're serious about this scenario with unforeseen circumstances and sitting on the balcony, then okay, we'll work according to the first plan. But it's probably better to put the archer on the balcony as well - if anyone appears in the hall, they'll take him down immediately.