Generate ticket in custom table from Lifecycle Event activity in Journey

[servicenow_dev]

Hi,

I have a requirement to generate a ticket/case in a custom table in ServiceNow from Lifecycle event in a Journey.
The activity needs to be reflected in Journey same as any other fulfiller activity (for example incident) and show as completed when closed. 

The idea is that there is some activities that are part of the a Journey, but fulfilled by groups who already work in a custom table with already established way of working, SLAs etc... And the custom table we want to generate tickets to is in its own custom Scope.

So ideally we want fulfillers in custom table to keep working as they are already doing now, but we want the Journey Owners to be able to follow these tickets in the Journey same as they do with other Fullfiller activities.

I have tried to create a new fulfiller activity type that uses template and noticed that the non-HR tables available to choose are limited to just change_request, incident_task and incident.
From my small testing all seams to work fine with incident_task table. But I wonder if there is any specific reason for this limitation in table choices, do the underlying Lifecycle event workflows NOT work correctly with other tables?

Would be great if anyone can suggest what is the best way of achieving this and does it lead to customization of Journey widgets in portal.