@Velsy:
A person in unusual clothes who is shouting in an unknown language runs towards the city gate.
What should the guards do with such a suspicious person?
Of course, he will be secured to avoid that kind of suspicious person to do any crime in the city.
Then the female knight takes him out of the prison to a place that can help to communicate with that person.
So the female knight brought him to the church where someone could use magic to create a translation effect.
In our world the police would try to find out what language that person uses by recording and then checking it.
Then they would call for a translator or organize a phone or video call with a translator.
The female knight simply did the same - just the way they do it in their world.
Also with the knight's strength she could be sure that he cannot get away.
After all if the MC really had the ability to escape her then he would not have been caught in the first place or already escaped from the prison.
As for why she brought him to the church for communicating with him.
A person unable to speak the language in that area appeared and she is ordered to find some bandits and get rid of them.
So she probably assumed that a person who cannot speak their language suddenly appearing there might be linked to the bandits.
She probably hoped that he was a slave or otherwise captive person who was caught by the bandit group but originated from a different country and then successfully ran away from the bandits.
And as such if she could talk to him she probably hoped to get info on the hideout of the bandits.
But after hearing his story she gave up on that hope cause he was no captive of the bandits.
Yet, fortunately for her, the MC actually encountered the bandits and knew their hideout.