There is an Anubi language, however only Anubi can use it and a select few half-breeds. There are under no circumstances any other subspecies of Pendragon that knows the Anubi language.
Anubian is not a constructed language. It is simply an English character rotation, or cipher. The cipher is as follows:
# Common (English) -> Anubian Cipher
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
O R S Q A G I B E G Z I J D U P T X C P Y Q H V N K