A: "Terrapin" was borrowed into English from an Algonquian word-- probably the Powhatan word torobe, which means "turtle." The Powhatan language is no longer spoken, but there are similar words meaning turtle in related Algonquian languages which are still spoken today, such as doleba (Abenaki) and tulpei (Lenape).
None of them mean "edible," "good to eat" or "tastes good," though. They only refer to turtles. The Abenaki word for "good to eat" is wigatôzo.
Hope that is interesting to you. Have a good day!
Further reading:
Powhatan language
Abenaki language
Lenape language
Native American turtles