Is the name Mirri only for cat? Or, A human female or male can live a normal life in Suomi with this name?
Mirri is a pet name for a cat. And for a particular part of the female body. So no, a person wouldn't be called Mirri.
Mirri is again in trouble was marked wrong. It seems that Mirri is a habitual trouble maker so emphasis on "again" should be acceptable.
I wonder if Meowth is called Mirri in Finnish