Yea that would be the correct pronounciation of Mirai. Except maybe roll the r a bit. Well...I'm having trouble describing it, but the Japanese r actually sounds a little bit like an l. But Mih-rye is fine. I do quite like it though.
I'm having real trouble saying all of the others though. Miriana is nice, although I always quite like
Mariana.
Meira is okay but NMS.
I don't follow the popularities of names that much but I think maybe if a name is really low down on the charts it can change it's position a lot for no particular reason. Looking at the origins of
Mira, it doesn't strike me as a name most Americans would be familiar with.