The instructors didn't know before hand that the difficulty was gonna be like this??
Well, not everything goes as planned in life
There sre bound to be unexpected situations. So you've to be prepared for the worst. Now imagine if raon wasn't there? Both training hall 5 and 6 would've been wiped out! Who'll be responsible for their death? They were just trainees meant to kill some orcs. But they had to fight some big shaddy organisation instead.
Well looking at it now, if raon wasn't there, they would've just gone home thinking their mission was over and the whole village would have been annihilated.
Which is why there's a protocol, such as secretly following and watching them from behind while they're doing their mission. Not just let them go to their first mission on their own while he catch up on some beauty sleep, slacking of. He almost killed an entire generation of zieghardt disciples ffs!
These instructors are so careless bro! Especially lumer! I know this is their mission and you're not supposed to interfere but at least keep an eye on them?! This mission is too high level for them to handle! He better get his ass whopped by grandpa zieghart or i won't be satisfied!