UPDATE:
Unfortunately, it doesn’t look like there will be a solution to this from Wave’s side anytime soon – although they were happy to hear my suggestion:
“Thanks for putting this on our radar. To my knowledge, we’re not looking at changing the formats accepted under the date for .csv file uploads, but it’s good to get a thread going to see if there is any other interest from our users for this.”
Here is where I posted it:
https://community.waveapps.com/discussion/comment/27137/#Comment_27137