They were absolutely not drawn in the middle of the physical sidewalk, because you were not using the correct imagery offset as described in my comment to you. You also drew the curb nodes directly on the sidewalks, as I talk about in my guide as being something that we are trying to avoid in Montréal. There were also issues with the tagging. If you'd like to contribute sidewalk data again, please make sure to use the correct offset, and take a look at the mapped sidewalks in Rosemont for a template that you can examine the tagging on.

Please tell your professor that the OSM community would appreciate it if they would provide better training for their students before having them edit OSM. (Discussion here: https://community.openstreetmap.org/t/current-influx-of-students-mapping-poorly-in-montreal/120635)

There are ways to allow students to work on an OSM sandbox that doesn't make actual edits to the data. This would be a better option for your professor, if they do not wish to carefully validate edits. I have already spent several hours of my personal time fixing errors, and would prefer to avoid spending more time doing so.