how to just find keywords just from “Text” and “Extra” field
This looks like a Anki issue, not an AnkiHub issue.
You can find this information on the official Anki manual here under “searching”:
If you cannot find a proper solution, you can try posting on this official Anki Support forum to remedy your issue.
Use the “BetterSearch” addon. You can search by note type field
Anki: Better Searching Tools: Anki: Better Searching Tools - YouTube