Creating fade out custom lines and curved beaming

I was wondering of there was some way to create a thick black line that slowly fades out?

For context it’s gonna represent the brightness of the sound when blowing in a flute (from darker to lighter sound).

Secondly I was wondering if there were some way to create curved beaming?

Thank you.

Welcome to the forum, Per. I’m afraid there are no built-in features for either of these notations. You should be able to achieve the black line fading out by importing a PNG file that you have created in an external application that goes from completely opaque at one end to completely transparent at the other, with an alpha channel background; but unfortunately you can’t create anything like that directly in the software at the moment.