Automations do support adding Checklist items, but at this time you must know the value of the Checklist item and hardcode it into the Automation because it doesn't support dynamic values, at least not yet anyway.

If you have the ability to bring the text that needs to be added as a Checklist Item into a regular Text field first, you could theoretically build an Automation combined with a third part product like Make.com or Zapier. Here's how you could do it using Make:

Create a separate App called \"Checklist Adds\", which has 3 fields.
1. Linked Record or a Text field which references the Title of the Record in the App that contains the Checklist field.
2. Text field containing the text you wish to add as a checklist item.
3. Yes/No Field indicating whether the item was added.

Using Make.com:

Set up a SmartSuite Watch New Records module for the \"Checklist Adds\" App. (This runs a Scenario any time a new record is added to the App)
Set up a SmartSuite Update a Record module to add the checklist item to the record containing the Checklist field.
Set up another SmartSuite Update a Record module to set the Yes/No field to Yes in the \"Checklist Adds\" App indicating that Make received the request and adding the Checklist item was successful. If Make cannot get as far as setting this field to Yes, chances are it failed to add the Checklist item so at this point you'd check manually or build more logic into the Make Scenario. I'd just check manually.

Hope that helps and makes sense!

Any way to turn fields into a checklist?