None of what you said makes any sense to me. Of course EU states are very different right now, and the language barrier is huge.
I'll say some debatable things now but I don't want to write a dissertation so i need to take shortcuts.
To unify Europe for real compromises must be made and an european identity must be created, the USA pulled this off almost entirely thanks to having a shorter history and also thanks to things like hollywood pushing calculated stereotypes (an arguably positive form of propaganda). European populations have been fighting each other for thousands of years so it will take some effort, but I think the reciprocal hate is at a legendary minimum nowadays, and there is a lot of mobility.
I may agree that going straight to unification may be premature, but to be honest the usa have a great deal of diversity and still make it work.