I’m not saying it’d be easy, I’m sure it’d happen after a whole lot of investigating, spying, negotiating, plotting, probably threatening, etc but it’s like kakyu said once he’s found out the jig is up and his relatively peaceful life is over and I think it’s the same for ars, no matter how powerful they both have blind spots and others important to them could be targeted
Demons have every reason to fear what just happened to the bug general and his most powerful subordinates. Even more so with how short a time it happened in.
"Did you hear, that ridged bastard Theokia got fucked up bad and was dumped via portal in front of the demonlord's throne... He claims to not remember what happened, but keeps muttering about this strange moving image with a little yellow midget who is writting "stay the fuck off my lawn" over and over on a black wall..."
As for the opinions of other nations and that of his own, there is no information, yet. Other nations would have to go thrue political channels for information, if they cared at all. His own is just a matter of reporting to his monarch that an experiment went sideways, with only some collateral damage to his villa, or honestly say there was a demon attack and was handled.
For the family thing I’ll admit it’s a stretch but I have no doubt ars will be told of his birth family, kakyu’s guilt won’t allow him to keep ars from knowing about them, while that won’t change anything about their relationship I can see kakyu omitting certain parts or the holy kingdom disputing things in ways that make kakyu seem like the culprit, it’d be dependent on way too many things that haven’t been revealed or addressed yet about the holy kingdom so theorizing is kinda pointless but it’s whatever
Frankly think it's a complete non-issue. The only connection is a prophecy of a hero's birth, them sending out a collection team who may or may not have reported purging a village, and their subsequent annihilation. The connection is even further muddled by a full on active war against the demons in response to the weird mana signature. So while there is always that non-zero chance the author will force the cliché, it's gotta be really low.