Sorry, but I don't understand what you are telling me.
If on my test system I tap "Change Library" then I see the following:
I can then tap the library I want, in this case the second one, in which case the library changes. After I do that then I see the following:
and I am looking at the books in the second library, exactly as I expect.
What exactly are you seeing?
If you are saying that you are not seeing all the libraries on your computer then the answer is "you are seeing all the libraries that calibre knows about." CC asks calibre for the list of libraries. Calibre gives back to CC the libraries that are on the calibre "quick switch" menu. There is nothing that CC can do about that. Instead, you mist be sure that the running instance of calibre has all the libraries of interest in its library change menu.
As for
discrimination, CC uses what calibre gives it. Calibre
does not like path names with non-ascii characters in it, and never has. Again, there isn't anything that CC can do about this.