Charles appears to have really made a huge effort to welcome Meghan
Well outwardly maybe. He had apparently nicknamed her “tungsten” before the wedding, which she obviously thought was a compliment, but in truth it’s rather a barbed one. I think he had her pretty sized up from the start, so has probably extended the niceties and be gracious, but I doubt he was ever actually pleased about the match. The Queen is similarly astute.
So I suspect all the main royals (ALL the royals?) had grave private misgivings, but scrupulous good manners. They knew they couldn’t stop Harry marrying her, so they had little choice. If they had put up objections he’d have huffed off to Canada or Botswana and married her elopement-style. Then the scandal would have been completely unavertable. The palace probably hoped to quietly manage them, but they refused to cooperate.