I don't believe this has been confirmed, then again I could be wrong. I think it's been confirmed (in the last chapter no less) that a titan of royal blood coming into contact with a non-royal founder is enough to activate the powers of the coordinate, as if the founder was of royal blood to begin with. So what happened when Eren contacted Dina probably was the real thing and not a lesser version of the founder's powers. IMO the spark that all the shifters felt at that moment meant Eren's command got to them, but they were not mindless titans and so couldn't be ordered to carry it out.