What are sub-accounts, and how do I upload Sentral CSV files?
Sentral does not currently pass through sub-account information to Canvas, but you can still allocate courses to sub-accounts using the CSV files that are generated by Sentral. After you have completed a sync from Sentral to Canvas, click on the Get SIS Import Files button to get an email sent to you containing a zip file (which contains the CSV files being sent to Canvas). Note that the information in the CSV files reflects what was sent in the last sync.

The courses.csv file may not contain the column that you will need to add the account details that you want each course to live in. This column has a header called account_id and should contain the SIS IDs of the accounts you want to link each course to. If you do not enter a value in this column next to a course, that course will be in the root account of your Canvas instance.
You can create account SIS IDs either in the user interface or by creating an accounts.csv file to import into Canvas. Here is the guide for creating CSV files to import into Canvas: How do I format CSV text files for uploading SIS data into a Canvas account?
You can also modify the SIS ID of an account in that account’s settings in Canvas:

Adding the account_id to courses only needs to be completed once for each new course being added to Canvas, which is usually at the beginning of the year or in the middle of the year for courses that don’t start till the second semester. Sentral will not override the account information when it syncs data to Canvas.