Hi, welcome to the forum.
I can’t answer your question about the Nuendo mini which I think will depend upon your DAW, but on augmented chords there are a number of ways to introduce them into a progression. There is a tutorial on adding augmented chords here.
There is also a short tutorial on adding custom chords ( including slash chords) here.
As a new user, you may also find it helpful to work through @davide’s videos on YouTube if you haven’t already looked at them.