Currently you can only set 1 default workflow in a Customer/Contact Project Template to be auto applied when new projects are created through the PCF / API.
It would be useful to allow for setting multiple default workflows, depending on what Service (or other trigger) is selected by the customer. For example, if the customer selected 'Translation Only', it would use a pre-made 'Translation Only' workflow template, but if the customer selected 'Translation and Proofreading', it would select a different workflow template to auto apply.