I think you could gain a closer perspective by starting with a description of the unknown sound that wakes Bernice. Maybe she could realize what it is when she hears the shout of the centurion? Does she grab a robe or something as she leaps from bed?
Also you might avoid passive voice if you replace "They have been dreading..." with something like "In the months since the family escaped...they've dreaded this moment." And maybe flip the sentence that follows to avoid repeating months--Four year old Bernice and her five year old brother, Junior, spent much of their time hiding in the shadows listening to the worried whispers between their parents. Secrets, spoken in Latin, not meant for the children to understand...
Just a few ideas I hope will be helpful. Obviously, they might need some serious rewording
One big thing that stands out--Bernice is four? If this is a book for young readers, I think the language is too complex. FWIW, I would've kept reading to see what happens next!