Dear ptutt,
I am a PE user, not one of the developers. But I think I can give an at least partial answer.
PE uses Open Sreet Map data for its maps. This is a project created by volunteers all over the world, adding data as they can. Coverage will vary, just as it does with any mapping application. I also have seen that, for one reason or another, coverage of Turkey is not as good as we might hope.
But no, a PE map is „the“ map, and there is nothing else to download. Perhaps you could join Open Sreet M ap and help the community add information? I’ve a tiny bit!
Yours,
Bucky Edgett