Since its release, the calculate fields has been useful for some basic calculation cases in the grid. We have re-visited this module and add date/date fields in the calculated fields option.
But yes, it’s not as strong and robust as it should be. I think calculating with Level List Field is a good use case we could think of. You could follow the post below to submit your use case as feature request. Remember to describe all your use case as detailed as you can.