1) Why not: "Are you coming INTO the zoo, too"? You ask someone who is outside the zoo to come inside. 2) "Are you coming to the zoo, too" (but maybe not enter) should be translated as <<Ti is jöttök az állatkerHEZ>>??????
Okay,"all " might be necessary to stress the plural but what's wrong with also instead of too
Nothing is wrong with it, it's one of the issues that haven't been fixed yet.