Edited text for FAQs fall under the lang directory. Structure changes don't appear in SDK.
Though, this page says you have to manage FAQ text completely in studio: https://developer.khoros.com/khoroscommunitydevdocs/docs/about-the-community-plugin-sdk (under "when to use studio").
You can try editing a FAQ question and answer in studio, then importing the Studio plugin into your SDK and see if it gets pulled in under "lang". There is no other way to determine the FAQ text file names anyway that I'm aware of.