To show letters, one has to set up a grade scale in PowerSchool and then apply it to the gradebook.The grade scale can vary district to district (even though 10% per letter is common, some do vary that) or even teacher-to-teacher, but is still usually based on percentages (points earned / total points). PowerSchool uses number values by default because points earned / points total is both easier to implement and the basis for any grade scale a teacher/district chooses to implement.
Since users can set up a Grade Scale on Canvas, when communicating between the two systems, the values of points earned and total points becomes easier and a more reliable set of values to transfer. Otherwise, both systems would have to start syncing grade scales on top of other values. If there is a mismatch between scales, that could add another error.
I am not aware of a way to fix your concern.
Is it a bad idea to incorporate grade scales in the data transfer...I don't think it is. I'm sure the engineers could figure out a way to make it work. But that also involves another level to account for in the communication scheme and another point at which Grade Sync could produce errors. BOTH Canvas and PowerSchool would have to agree on best practice for such a feature.
You could suggest this as an Idea for consideration on Canvas: https://community.canvaslms.com/t5/Canvas-Ideas/idb-p/canvas-ideas
Since this would involve both parties, you would also want to reach out to PowerSchool to suggest the idea as well.
