I time traveled forward about 6 months (day by day by day, quite the grind) to get a thought bubble for Tangy, and before I was about to give up, I noticed that there was a villager in my campsite! Inside the tent was Ankha, and I took the opportunity to kick out Tangy once and for all. After another 2 hours of playing those stupid card games with her, she FINALLY agrees to kick out Tangy! I accept, of course, and set my switch back to real time and reentered the game.
When I came back, I noticed that Ankha had moved in, but her house exterior was the same as Tangy's! Not to mention, when trying to enter Ankha's house, I was met by the obligatory "I'm out doing dumb stuff, come find me" note, but she was no where to be found! I searched everywhere (yes even in the museum) and she was gone. At this point I was real scared, but time travelling a couple days into the future made her reappear no problem.
Her house exterior is still identical to Tangy's, but her interior is fine. I did some web surfing, and it looks like the reason this occurs is when a villager is forced out of their house, either by campsite or amiibo, and then you time travel backwards before the moving is complete, the house is forever bugged until you move them out. I was just gonna post this to see if there was a fix without moving out Ankha, because she is kinda expensive lol
Edit: Omg it turns out that Tangy's exterior was bugged AS WELL, and is IDENTICAL TO CHERRY'S EXTERIOR. So maybe if an exterior is bugged, it is forever bugged? This really gets on my nerves because I have Cherry again, and now I have TWO IDENTICAL HOUSE EXTERIORS. Pls help
