Most characters are referred to by their Greek names such as Zeus, Hera, and Ares. However, Hercules is the Roman name of the Greek figure Heracles. Most modern versions of the character do this for marketing purposes.
Characters often measure distances in the metric system which was gradually developed in the Renaissance, perfected in the late 18th century, and made internationally popular only in the mid 20th century. It can be assumed that conversion to modern units is part of the "translation" we are hearing of what they said.
Aphrodite refers to Hercules as both "older brother" and "younger brother" several times throughout the series.