Jagged curves
Hello, anyone know how to turn jagged curves in to smooth lines in Illustrator please?
I've created this design in an A4 template - starting with pen tool > stroke > custom brush > expand in to shapes > make compound path > make clipping mask (with a custom blend)

When it was just the original strokes, the curves were still not fully smooth either, but a little smoother than the above:

Anything I can do to make the lines nice and smooth? I've tried even just using a basic stroke in case it's the brush I've applied, but even that struggles to make smooth curves (and doesn't create the tapered lines I wanted...)

There must be a way to get curved lines all smooth surely? Can't work out what I'm missing... help please?!
