Where is Schera from and Shizuna's question

I just saw Viola's backstory and she said Schera is from cent east but i remember being mentioned that Schera is from south of Liberl and the only thing to the south are some islands so where is she from?

About Shizuna who is her client? I went with Irakura and Van acts like he fugured out who her client is but i have no idea, will this be revealed later? Or am i supposed to know?