I'm sorry to hear you are experiencing challenges with Y over Y and YTD calcs in Tableau. I have reviewed the attached workbook and see that for each Event, there are potentially, several orders dates. There are not other values at the level of Order date as well.
Is the desire to bucket together the yearly sales by order date then? if you bucket by Event Date as is done in "All Dates" then the order date information is lost/ignored. It sounds like this is an issue but for some reason, the use of Order Date is not an option.
could you share a few more details about this setup and how/what limits Order Date from just replacing Event Date in the views?