"Blue" isn't a translation of "Sultan Ahmet" at all. This is an example of different cultures assigning completely different names to the same landmark with neither side being aware of what the other calls it. Another example is what our guidebooks call the "Sphinx of Giza"; whereas the locals only know it as "Abu al-Hawl (Father of Terror)," for reasons one can only guess at. ;-)
Ektoraskan, do you mean that Sultan Ahmet is considered as an adjectif? If it is the case, for which reason the posessive suffix at the end of "cami"? "His big room" = "büyük odasi (pointless i). May i conclude that "Sultan Ahmet" is the equivalent of "büyük"? That "Sultan Ahmet" does not represent the ownering person of the mosque?
If I remember correctly, the small prayer rooms found in offices, many hotels, as well as truck stops and airports are "musalla," in Arabic, while a larger facility for a neighborhood a short walk from one's house is a "masjid," leaving "jami'at" (plural of "jami'ah") as the big places where a whole town or a section of a larger city goes for jumu'ah prayers (note the common root J-M-'A). However in Arabic at least, all these entities may be called "masjid" (pl masaajid), where people "jalasa" (bow down) before Allah. "Mosque" appears to be some European's mishearing of "masjid."