We will need to implement the new way of abstraction (T246800: Abstraction layer in SearchEntities API module) to call a remote wbsearchentities API and return the result to the user.
This would plug the request parameters into the new http client (will be done in T246802) and transform the response so that it is usable with the new abstraction.

As noted in T246800

One thing to note as discussed in our in person meeting is that either here or as part of T246803 we will likely have to loosen the requirement / mediawiki validation of the languages parameter on initial API input.