This is stated: Note: If you want to assign goal revenue dynamically, you need to [track a goal manually] and [set a variable] that will hold the revenue value.
But on this page:
It is only described how to setup this through Piwik PRO Tag Manager.
How can I send a goal manually to Piwik PRO with a dynamic value via javascript in Google Tag Manager?
I know how to send a custom event from GTM - but then Piwik PRO does NOT use my event value as the Goal value.