It hadn't occurred to Tony that there would be a problem of 'getting away with it' at all, like it could have been unnatural that the Scarlet Witch and princess of if not Genosha then definitely his house and then Avengers Tower hadn't been born wearing a crown. She certainly had the carriage for it, enthusiastic flailing notwithstanding. It was a big change after her reticence, though, and Tony was glad enough for it to grin back with all of the self-assured pride that should have accompanied his presentation, but it grew brittle throughout her kiss and had to be covered with a mock sobriety for this momentous coronation. He should have been able to give her anything she wanted, anything any of them wanted, all along without having them grow frustrated with him. After all, there was nothing really stopping him from taking it during the plague-- but then, there was nothing stopping the Avengers, either. There was no real way to justify his place on the team.
In French, Tony anointed, "Praised be the princess Wanda, governor of this land and ridiculously slow elevator, may she rule with dignity and justice and fantastic breasts for all of her years to come. Amen," and placed the circlet on her head, carefully smoothing her hair and arranging the ruby between her eyes. It really did suit her, though maybe would tie in better with the Scarlet Witch's costume and hair flying in the wind as she hovered over her kneeling subjects. Who was going to say no to that?