I believe most dates in the frontend are already formatted according to the language. Mostly it's using the "ago" time from moment.js. It's correct that we can't customize anything per region right now, unless you split for example en-US and en-UK
There were some existing discussions about specific areas that can't currently be customized easily. I remember discussing the date in the scrubber, which is manually crafted and the month and year order can't be switched by language packs.
If I ruled the world, I would enforce something like YYYY-MM-DD everywhere. MM DD and DD MM is such a madness when you don't know which format you're looking at 🙄