The Language class should not depend on the Title class. The only non-deprecated code that currently needs the Title class is code that delegates to LanguageConverter. Such methods in Title should be deprecated, callers should be changed to use LanguageConverter directly (or a more narrow interface derived from that class).

Note that Language will (for now) still need a LanguageConverter instance, but it should have no need to call any methods in LanguageConverter that need a Title object. Perhaps a new interface could be extracted that covers just the things that Language needs.

See also T226834: In LanguageConverter, replace usages of Title with usages of LinkTarget