I have to admit, I'm kinda hate reading this story now, because I just cannot stand the MC's attitude, even though I know it's largely forced. I just hate those kinds of people in general and I find it hard to believe that even as godly powerful as he is (and let's face it, he's OP enough that that man daring to challenge him is basically just a death wish) that people would just shrug and accept it after a bit of moping. Like, he's talking so much shit and NO ONE visibly holds a grudge? Sure, they might wince in fear or there might be the occasional mention of it happening off-screen, but none of that has been reflected on the page yet. to me. Everyone's just smiling jokey when I have an exceedingly difficult time believing everyone would just brush his statements off. I don't think he gets any better, but I'm at least hoping he gets his block rocked at SOME point.
He's not godly powerful yet. He's painfully aware of the fact that if Justus happened to pay him extra attention right now, he would lose automatically. That's also why he won't go and confront Justus, even though he knows all this time Justus is busy causing trouble and building disasters. Harold simply isn't powerful enough to survive that meeting.
I consider his forced, disagreeable personality one of the best parts of the story. Sure, you have to stretch your suspension of disbelief a little bit, but not as much as you suggest. At the end of the day, he's the first in line in an infamous noble family. Secondly, he's not a windbag. He has the strength to back his foul mouth. He also gets things done. The Sumeragi gladly tolerates his attitude because the Sumeragi hugely benefitted from his advice, as he basically saved the Sumeragi domain, and wasn't even a killer, despite the rumours.
Usually when an isekaied person takes over a character, nothing of the original is left, aside from the body. This is a rare example.
Exactly this. That's why he's working so closely with the Sumeragi(?) family now and is accepting the help of their operatives for this.
He realized it can be changed and he has changed it and he's been aware of it for quite some time, now. Of course, he'll still be dense as fuck when it comes to Erica and realizing how much she supports him because... male isekai MC... but at least he's realized more than most MCs. And, y'know, actually plans and prepares for things. As far as isekai MCs, he's a a damn genius.
I can somewhat forgive Harold appearing so dense because he believes Erica is forcing herself for the sake of her family. After all, Harold still hasn't noticed the Sumeragi family knows the truth about the faked murder. The supposed unjust murder of a servant was what made Erica really hate Harold, at first. Furthermore, Harold has been adamant about isolating himself up until very recently. He dislikes Harold's character himself, he dislikes the Stokes family and doesn't want to drag anyone into the Stokes family's degeneration, he has to be extremely careful with his game knowledge. So, it's not as much about being dense as it's about believing it's for Erica's own good to have nothing to do with him or the whole Stokes family.