The implementation of NIP-50 is usually fine, I think. The main problem is that clients do not use it, and the custom search approaches are rather inaccurate.

My basic test is searching myself by display name (since it's more common), adding a word from the bio; using the name (that on Nostr is not unique, of course), plus an additional keyword should be a basic way to find someone. Example:

nak req --search "daniele gossip" -k 0 wss://......

Results:

relay.nostr.band: found

nostr.wine: found

relay.noswhere.com: error

search.nos.today: zero results

50% success, not exceptional.

Let's see how the search for "daniele gossip" works in some clients:

Coracle: zero results

Nostrudel: found

Snort: found a note, not the profile

Primal: found a note, not the profile

Habla.news: found a note, not the profile

Gossip: zero results

Amethist: zero results

Voyage: zero results

Nostur: zero results

Damus: not found

10% success, disappointing.

Some clients work better with a single world ("daniele"), but it's just a casualty, since a single keyword is often meaningless without a context or a proper sorting.

Weight fields, proximity or fuzzy full text search are still science fiction.

I will do more tests.