Let content packs add patches which are conditional on context like season, date, or language.

Done in develop for the upcoming Content Patcher 1.3. This adds a new When field which supports comma-delimited values for day, day of week, season, weather, and language. See the readme for more detailed documentation, including how this affects loader validation.

The Locale field is replaced by the Language condition; I'll check all the content packs to make sure none of them use it. (If some do, I'll add a backwards-compatible field.)