Quick answer
Use the KeepNest library search to find words in the content already saved in that browser. Choose a short distinctive phrase, inspect the matched excerpt and open the original source when needed. This is local keyword search, not semantic search across every bookmark in your X account.
If a reference does not appear
Switch to All before assuming the item is missing; Recent shows only the latest 30 matching saves and Read later only marked items. Try a term from the original text rather than a remembered paraphrase. Check whether the content was saved, is only in the temporary review queue, or was never captured. A source URL and a JSON backup help distinguish those cases.
