I don't agree with your last comment here.

The fields in this function are the 4 fields for which it makes sense to do analyzer "upgrading" on. These fields won't change until we change the indexing of the models again, such as when we turn on localized search for Questions, and no matter what we will have to touch multiple parts of the code (including wherever this logic lives) to make that change. The query performed doesn't matter. If they query includes any of the four `l10n_search_fields`,  that portion of the query will be modified.

This function is also tied closely with es_analyzer_for_locale and AnalyzerMixin (and thus AnalyzerS and the new Sphilastic), which I would argue all should be in this file, so I think this is the appropriate place. If it must move, I could imagine this code living with the models, where indexing happens, but not with views.