I wonder if Iroha will end up make a body for Yachiyo, too.

Who do you think is inside the Kaguya body?

Serious answer : Yaccho can duplicate

Which is why Kaguya and Yachiyo appear at the same time at the end of the movie, even though they're actually a single entity.

Somehow this gets a lot people confused.

Well, they also let some mystery about what the lunarian actually are. We can pretty much guess they are alien numerical entities but we don't have more information. It's mostly small details spread all around the movie and the novel that make you guess that. This mystery about the lunarians (and by extension WHAT kaguya/Yachiyo is) is intentional

Also, a lot of people do tend to forget that Kaguya isn't human.

So yeah i'm not surprised the ending get people confused.

I was confused about the ending because the new Kaguya body was acting like Kaguya rather than Yachiyo, which doesn't make sense to me.