The Configuring terminology documentation is currently focusing on what changes are expected with the new Terminology but not what's expected to remain the same, like:

• JQL searches (advanced search)
• REST API queries (use JQL, same as above)
• Custom field names (they remain Epic Name, Epic Link, Epic Color, etc)

We could make it clearer the Terminology feature in Jira works similar to a frontend/UI translation layer.
It changes only the Epic issue type name to the new terminology, leaving all Epic-related field names the way they are.
Even for the Epic issue type, only the output is translated. The input still requires the Epic keyword like in:

resolution = Unresolved and issuetype = Epic

Basic search (works with Feature)	Advanced search (needs Epic)