I was going to complain about how i was supposed to know if A is in B when both A and B are red links, but now i changed my mind:
The characters outside ascii have the wrong encoding, so when asked about Ciudad_Juárez (Ciudad_Ju%C3%A1rez) it is named, and the link points to Ciudad Ju??rez (Ciudad_Ju%3F%3Frez) As á is %E1 i have no idea about how you got that wrong encoding, which should have been managed by mediawiki. :S