You should note the following issues:
Don’t use excel to edit reviews export file
After export customer reviews from Ryviu, please do not use Excel to edit. Excel will change the format of CSV file and you will get notified when trying import to Reviews Product app by Shopify.
You just use Google Docs to edit the CSV file, or you can edit customer reviews on Ryviu Dashboard as easy.
Don’t click on US date format checkbox
If you want to change the date format of customer reviews, you can change it on settings of Reviews Products app by Shopify.
Don't hesitate to contact us if you need help.