I changed the title of one of my documents to “The OpenBSD 4.0 Crash Course”, then searched for “openbsd” and EagleFiler found the document. So I think this works. Just as some background, Title searches work differently from Anywhere searches. A Title search looks at the exact title of the records, whereas an Anywhere search is a word-based search that uses an index.
As I said, an Anywhere search should be able to find “openbsd”, though there are a few caveats. First, there will be a slight delay between the time when a record is added (or the title is changed) and when that record is up-to-date in the index. This is usually about 10–15 seconds. Second, it’s possible that your index file is damaged so that EagleFiler was not able to index the document, or so that the document is in the index but can’t be found. If you close the library and delete the Indexes/Records.efindex file inside the .eflibrary, EagleFiler will rebuild the index the next time you open the library. Please try that and let me know whether it helps.