I posted details of this (including screenshots) in the bug report thread. It needs to be treated as a bug because that’s what it is, regardless of the developers’ intentions in changing the animation time. Eating is so fundamental to the game that it isn’t something that can just be overlooked for non-default day lengths.
I really hope they’re not going to stick with ‘this is intended behaviour’ as the response because that’s just not acceptable. If so, other people might have to start making their own separate bug reports until someone on the dev team gets the picture.