"I hide gems and rings in the house."
Translation:Gemmas et anulos in villa celo.
You're initial assumption, "Maybe because domi implies more home" was also mine. That certainly appears to be how it's being taught in this course, and it's also what I've understood from elsewhere.
However, there is also a noun domus meaning house. It's usage appears to be complicated, having a combination of 2nd and 4th declension endings. I get the impression that it's usage also changed over time. These reasons probably explain why we have not been taught it in this course and only villa is being used as a translation of house, whereas in Roman times I believe villa was used only for a large country house, and presumably not the sort of house you'd get in a town or city street.
As you also said, an explanation of why you're comment was downvoted would be more interesting, because I don't think my contribution really answers that, in particular whether domi can mean both at home and in the house. To my English based way of thinking these two phrases don't have quite the same meaning, but it would be wrong to assume that other languages work in equivalent ways.