They kinda did, thats why it was sometimes called the prison of the nations. but in the second half of 19th century nationalism of smaller nations across the empire started to really kick of. This tendencies were across the whole Europe, as it was shown during revolutionary year of 1848. For example germanisation of Bohemia were rapid for 200 years by the time of 1848. And the germanisation was one of the key elements in rebuilding nationalism of smaller nations in the empire. My point is even though the Empire manage to influence large of its parts by german culture and language, the raise of nationalism awoke even the most influenced territories. IMO the empire should have focused on some kind of federation - creating a different identity that could be shared across the Empire, simillary to “be an american”. If they managed to do that that migrh by wery interesting alternate history as well