Unfortunately documentation is not really great - I think development is at higher speed than product management at Lumiite. But I figured it out thanks to a hint in Facebook. Te extra press actions are available on preset level, once you open a new event in the preset editor using the "+" sign and then click on the default "CC", there are three pages of event types and on the 3rd page or so are the extra press actions, you define one, like for example "double tap", and it will then trigger the event that is placed after that one.
So I managed to have one click load a preset on Anti and set delay level on Starlight, and double click do the same but also activate modulation on Astra. Pretty cool once you know how it's done.
They should get their act together and significantly improve the manual. It's such a powerful system, they should make it more accessible.