Hi Paul,
“Is there a way to enter data to the Data Table particle other then trough the UI?”
Sure but it requires technical skill. If you interested in modifying Outlines outside of the Gantry 5 administrator, please navigate to your /THEME_NAME/custom/config/outline_id/layout.yaml (particle data are stored via layout.yaml )
Please take a look this screenshot https://imgur.com/4FbiY9n

You can find the layout ID via URL, example
http://localhost/particles/administrator/index.php?option=com_gantry5&view=configurations/31/layout&theme=g5_hydrogen&ba18df5ea9d033d20537f735e5a95480=1
So 31 is the layout ID that you are working on