I think it's good that you educate and train yourselves further in the profession. So to speak, trainee further training
No, after completing vocational training, it's advanced training or further education with the appropriate qualification or degree; there is no longer any trainee status, it has nothing to do with training anymore.
Be that as it may, the income is great and will still increase, that is the crucial point, because trainee salary is not counted as sustainable income by German banks.