I do not think you can have access the text presented by the DrawableOverrule, because it is a visual presentation dynamically generated at the time when the Overruled hatch needs to be drawn/redrawn, it could be any shape and it happens to a look like a text.
So, you can save the Text with XData/ExtensionDictionary to the overruled Hatch, of course. Or, maybe, for it to be a bit simpler, you can expose a Dictionary<ObjectId, string> from the Overrule class as static property, and save the text value used for visual presentation in the dictionary for later easy access?