I am not a lawyer... but then I don’t have to be to answer the question. Not being a lawyer I will not charge you (grin)!

No. Plagiarism is when you put the notes in the same exact order as some else has done and copyrighted previously. You cannot do it by mistake. Contrary to many claims — you know when you have stolen a composition. It doesn’t happen by accident.

If you use a Performance with Arpeggios... the Arpeggio don’t do anything without you. Even if they are recreating a Pattern that sounds like a song you know, you’d have play those chords and add that melody.

If it sound similar to an existing song, and you play the exact chord changes and melody of that existing song, you’ve got a problem.
But only if you play the exact same chords and melody. There are among the Motif XF Performances many sound alike Performances.
Dark Continent = Toto’s “Africa”
Jack Does it Again = Steely Dan’s “Do it Again”
Free Fall = Tom Petty & the Heartbreaker’s Free Fallin’
Rule the Earth = Tears for Fears’ “Everybody Wants to Rule the World“
Big Watches = Coldplay’s Clocks
Etc., etc.
There are Arps in Performances that recreate a Bossa Nova, if you play the chords and melody to “Girl from Ipanema” you will only have a problem if you try to take credit for writing it. You can play a gazillion songs with that Bossa Nova groove, you’ll *know* when you are treading on Antonio Carlos Jobim’s sacred ground. you’ll know...

You can use any of these freely — just write your own chords and melody!!!!

Thanks!

The MODX is so powerful and it is so easy to compose with it that I didn't want to believe it was so easy to do it. 😀