You can use the Sync options to enable "Filled out forms" activity sync to SFDC.
Is there a way to prevent select forms from triggering this activity instead of having it blanket enabled for all forms?
The only way to simulate this is to turn off the automatic Activities sync (the checkbox here) and instead push a task (Create Task in SFDC) conditionally in a Smart Campaign.
Does this activity sync auto create a task in SF? I've noticed in SFDC I have a task assigned and entered for every form submission. We want to pass additional information to this task but I'm not finding in my instance where this task creation is taking place.
+1 on Sanford,
Furthermore, it's not really recommended to use these automated activities. It will clutter your SFDC instance and make activities unusable by the sales themselves. You will end up having data space issues in SFDC.
Yeah, it's a lose-lose! You don't get everything, but you get things you don't want.