I understand how you want the integration to work seamlessly with QuickBooks. I'll provide some details about this, Cetanorak. 

When we sync or integrate, we combine two to more things to create a collaborative unit. Therefore, this needs specific requirements that will encompass complete data integration from all contributors to the process.

Since QuickBooks Online (QBO) is the software that receives the data, it relies mainly on the third-party application (Gusto). You'll want to reach out to Gusto Support since QuickBooks will only depend on the information that the application can share. This way, they can offer other alternatives for the contractors' names to be mapped on the QuickBooks name field.

In the meantime, I would suggest doing your way by revisiting the journal entry for contractors' payments to manually assign them.

Furthermore, you may also want to visit this page in case the previous application you're using doesn't work for you.  I've added this link for reference: QuickBooks Online Application. You can search for an application that works best for you. You can also check out its reviews and ratings to make sure you've chosen the correct application.

Let me know if you have any other concerns with the integration. As always, we're always right here to further assist you.