At least for EPiServer.MarketingAutomationIntegration.Pardot this is extremely stupid. Because of the validator on the "Column" dropdown when creating a "Profile/Database" visitor group we cannot use ANY of our custom fields on our prospects in pardot.

There is nothing in the back-end that is blocking this from working. I have been able to use our custom columns with these visitor groups by editing their definitions manually in SQL management studio like this:

SELECT pkId, String01
FROM tblBigTable
WHERE StoreName = 'EPiServer.MarketingAutomationIntegration.UI.Plugins.VisitorGroups.Criteria.Database.DatabaseModel'

String01 contains the column for the rule and by putting in our custom ones there like "MH_Predictor" and then restarting the site everything works. As long as you don't try to edit the visitor group any more through the EPiServer interface.

It's only the stupid front end widget that is refusing to validate and save custom values. Please remove this limitation. Either that or remove the hardcoded column values from the Pardot connector. They need to be configurable through a config file/through the web interface or actually queried from the Pardot API (shouldn't be hard should it? the plugin is already retrieving all fields from the users through the pardot API).