Some extensions would like to provide sane defaults for search profiles. In some circumstances these defaults may need some wiki specific configurations.
A real use-case is wikidata search based on statement boosting, the statements are wikibase QXX ids since those are installation specific the default profiles should not provide them.
The previous approach was to inject a custom rescore components using cirrus low level APIs. It should not be needed, extensions should not have to deal cirrus internals when they want to customize search profiles.

@EBernhardson suggested solution based on a xpath like syntax allowing to override the profile settings (i.e. injecting some new data based on external configuration).
A proof of concept is available here: https://3v4l.org/NtpGE