Based upon the following, 17.1.6 is the highest version currently fully supported and exposed in TestComplete.
https://support.smartbear.com/testcomplete/docs/general-info/supported-technologies/controls/devexpress.html
This does not mean you cannot work with the controls, just means that, as you discovered, certain things are not going to be able to be as easily identified in TestComplete.
One thing about Ribbon controls is that, for many of them, while you might not be able to access the button object itself, you might be able to use the ClickItem method or some other properties to identify and validate the controls.
