I changed this entity's alias (primary english alias - non default) and now it's not found in the search results searching for "Pani jeziora".
https://beta.bookbrainz.org/search?q=Pani+jeziora
Searching for "Lady of the lake" I do find it:
https://beta.bookbrainz.org/search?q=lady+of+the+lake

I tried changing the non-default alias to non-primary, but that hasn't changed the situation

However reindexing worked and now it's found by its default alias

Conclusion: when you edit an entity, it seems to be reindexed only by its non-default aliases ?