Is there a way to get back / retrieve a mysql root password.
I mean get it back : not resetting it (I already know how to reset it and I use the reset method currently).
I usually have moderate success retrieving lost root MySQL passwords from MySQL history logs (e.g. .mysql_history log files). Also frequently applications are also a data trove for finding privileged passwords. Often root passwords are (mis)used for applicational use. Also, more rarely, as @Luciano says, you can also found MySQL password(s) in the shell history logs, if the user is not careful and uses the password in the command line.
As for the actual MySQL user tables, they are in an hash format. For practical purposes, it is not possible to get back the actual original password from there.
Unfortunately, as you imply in the question, failing getting the password from logs or applications (or from someone), the best course of action, is indeed resetting it anew.