Every time I have seen an rule regarding this infraction it is stated that the catcher obstructs the batter's attempt to strike or tap the ball or something along those lines. The definitions of the terms include for Interference, offensive and for obstruction, defensive. I have never seen it referred to as catcher's interference in a rule book. (Limited to USA and NFHS, I admit)
We are talking about softball, not MLB, it's a totally different animal. You will also find in their rulebook the term balk, that does not exist in softball. Neither does catcher's interference, it's catcher's obstruction because the catcher is on defense and the defense obstructs, only the offense can interfere officially in softball.