This is simply because the interface is in English and is supposed to be consistent with kjv. What are in some versions the books Erza and Nehemiah are in the Septuagit 2 Esdras. However these ...

1 Maccabees is one of the deuterocanonical books of the Bible. 2 Macc is not a sequel to 1 Macc. In fact, 2 Macc tells many of the same stories from a slightly different perspective than 1 Macc.