I forgot what's the exact thing that "Mine Event" do but as far as i know, that "Mine Event" grants you additional Ores when you claim a cave .. The Animation with Bento Box grants you additional percentage of making the miners mine fast .. The animation where the miner gets backache like onoki, gives you more time in mining cave ..

Yeah, since the first few days that featured was released, the animations of that Mine Events says something about what they do but today, it seems like that the animations has some kind of visual bug or error that not says what it does .. just plain animation without any description or something ..