This is probably my favourite part of the story so far. So many isekai have the MC fitting in more or less perfectly and it's mostly handwaved away. Having the MC's reincarnation being recognized by the characters in the story is refreshing, and I'm willing to bet that in later chapters the religious dynamics of the world is going to serve as more than just an easy justification for the conflicts between the nations. I'm willing to bet that since Schweidel is "Peaceful Rest" sect, and they fight against the Resurrection sect, that is going to cause some... problems.I'm finding it interesting how the Colonel is putting together that there are inconsistencies in Yuiner, but every single background check of him comes back clean.
He would give any competent intelligence agency head absolute fits, because he seems to be some kind of deep cover agent, but no agent with a cover identity and background so flawless that it would stand up to any scrutiny (because he really did grow up as a citizen of the empire with no contact with foreign powers or agents) would make the kinds of mistakes that he's made so far.