While it's possible today to automate the creation and updating of a MS Project using the Dataverse tables, this doesn't work for a system account, and this greatly reduce the usefulness of the API.

From the schedule API MSDN page:

The following is a list of limitations and known issues:

• Project Schedule APIs can only be used by Users with Microsoft Project License. They can't be used by:
• Application users
• System users
• Integration users
• Other users that don't have the required license

This functionality would enable automated updates of online project plans from external system.