Have you ever tried using the Mastery Outcomes in Canvas? It can be a huge hassle, especially if you want to create your own rubric scale for each and every single outcome. This is an Excel spreadsheet that you can use as a template to help you with creating a large number of Mastery Outcomes in Canvas. You will have to Re-Save this document as a CSV file once it is downloaded and then when you Import the file you will need to make sure that you select the CSV file.
If you have any questions I have a YouTube video that explains the process of modifying this CSV document, which will be available for free on YouTube.com.