Currently, validation does block invalid operators in conditions for day-2 and delete actions, but it doesn’t block invalid property names. This means you can successfully save your action, but when you go to execute, there will be no entities listed in the drop down. If you open the browser dev tools, you will see a "not_found" validation error for the property. This error should be surfaced when you try and save the invalid conditions block. You should not be able to save the action with an invalid property in the conditions block.