In my server installation, xapian's omega component is desirable to provide a little web search engine. Fedora includes several xapian components, but not that one. ISTM we might even include the xapian-omega source tarball as a part of the main xapian src.rpm, and build them together.
omega is shipped as a separate tarball [1] and as a result should be packaged as a separate rpm on it's own, not as part of xapian-core/xapian-bindings as per the packaging guidelines. [1] https://xapian.org/download