Ah, thanks for the reminding about General Broadcast. I know it for the execute flow workaround, but completely forgot it here.

But unfortunately this only work for Automagic. Tasker still can't create generic shortcut activity just like automagic can.
To execute flow from tasker (with additional parameter)
==========
Tasker - Send Intent
Action : automagic.yourflowname
Package : ch.gridvision.ppam.androidautomagic
Target : Broadcast Receiver
If you need parameter/variable get transferred, put them in the
Extra, there are 3 available. Should be enough, but if you needed more, you can arrange your variable in list format.
param1: hello
param2: %yourtaskervariable
==========
At Automagic flow, add
trigger : General Broadcast to the flow you want to call from tasker.
Action : automagic.yourflowname
If you use parameter, at the Access Intent Extra, put
value1 = getString("param1");
value2 = getString("param2");
==========
Action : automagic.yourflowname can be anything, just make sure it is unique and not similiar to any other usual broadcast. One of the naming convention will be automagic + yourflowname (without space), ex : automagic.openinchrome
param1 and
param2 can be other name, just make sure it is the same name at getString().
%yourtaskervariable is any variable at tasker
value1 and
value2 can be other name too, these are the variables available at automagic. You can name it as param1 dan param2 as well.