I just started playing this game, and I was thinking the same thing -- as far as the selling/ownership of the resort goes. There is no legal system in the world that would allow for the sale of a property if there are 2 owners of said property, and only 1 of them had signed a deal to sell it. And the MC has literally only seen the "video will" 5 minutes before his sister says that she sold it. How did she sell property that she didn't fully own, while the MC didn't even (probably?) get a chance to meet with the lawyers and sign the will and testament documents? Obviously, the transferal of ownership is the main point of the story, so it should have come out that Mio was a part owner of the resort already with the deceased father, and Gloria sold her "share" of the hotel to Mio, making her majority owner by %, and thus the "true" owner. This would be more believable and still keep Mio around to manipulate the strings, considering that Gloria really wanted nothing to do with the hotel in the 1st place, and wanted MC to leave back to Mexico with her.
Of course, if you suspend your belief of that, it doesn't really matter. But sometimes it does take you out of the immersion when something feels glaringly overlooked. However, I chose to ignore this minor infraction in order to enjoy the game.