It's kinda fucked that even though a lot of the characters are clear placeholders, they're already what the game is recognized by. Hell, he fucking sells merch and does collabs with shitty Western porn games using her character, which is still basically just the Aoi model.Honestly, some of the new models are so similar to the placeholders that it's easy to get confused. I didn't even realise Ayano's room got an original model - I thought Alex just moved the props around to make it look different. Alex clearly likes to have his own assets modelled after an already existing model instead of having his own designs. It also doesn't help that Yansim doesn't really have its own style - almost everything looks as if it was lifted from MMD/Custom 3D series.
Another thing to consider is that Yansim has been available to the public since its earliest stages. While it's a common practice for game devs to use models from other games (or simple geometry) as placeholders, the public sees none of that shit since the placeholders are always replaced by the time the game is revealed. And even if a dev doesn't have their own assets they just make some shitty models to replace them later when they get funding. For example, Paralives looked like trash and had the shittiest models when it was conceived but now it looks pretty good and they made do without stealing anything.