Is T143706 enough for this? Is that fast/ reliable enough to switch all of production to it or do we need another service for the use cases there?

If Elastic is not enough for this, we could have simple lookup table like:

entity id, term type-language, term text (where the term type-language field may also be a int hash for performance)
Is that enough? That only allows lookups with a enumerated term type-language set, not (efficiently) getting all labels from an entity or getting all Spanish terms.