Currently, Dealpos supports to export and import of data using CSV files. If in case you experience a messy CSV file format display, you can follow the steps below to fix up your CSV display.
Step 1. Open System Preferences Menu
Select Language & Region Option

Step 2. Choose Region option and search for America - United States
Your Display should look like this:

You need to restart your computer afterwards.

You might also like to these articles below:
If you wan to check for Windows OS you can go to Fix Bad Format in CSV File (Windows OS)
If you experience minor issues in using DealPOS, there is a possibility that the issue is due to the cache in the browser. You can try to clear the cache according to the browser you are using: Google Chrome | Mozilla | Safari.
If you can't access your DealPOS page, maybe you can try using Browsec VPN for a while: How to Download and Enable Browsec VPN on your Browser.