According to This answer there is a special reason why Shurelia is able to appear in Misha's and Aurica's Cosmospheres.
How in in the 4th Level of Cloche's Cosmosphere Mir appeared despite the 2 never having met. even if the reason for Shurelia appearing in other's Cosmospheres rings true for Mir according to this answer
Cocona is also an IPD, meaning she does not connect to the "correct" server, but to the Infel Phira server.
this means IPDs have a totally different server that they connect to plus Infel Pira was man made after the Reyvateils appeared (as Infel, a Reyvateil herself, made it to prepare to sing Metafalica)
So i am wondering how is Mir turning up in Cloche's Cosmosphere?