We had a meteor spawn earlier and noticed that the time it lists until the spawn is in-game time.
When you inspect a local resource with the inspection tool on the other hand, it gives you the real time.
Considering that the game has various modded clients available, which are all preferred clients over the vanilla client, and all of which can and do allow to mess with time displays to simplify the conversion, such as on curiosities,
I think the game itself should at least be consistent in the times it displays to be either real or in-game, as it's already quite confusing enough as is with everyone using different clients.