Closest/safest way is to literally add numbers to the course name and then do alpha. If you go style change routes it’s very easy to break, oldest/newest you can start strong with, but as soon as you have a slight issue in one course it all goes to pot….

I am also having this issue. I’d like to be able to move courses in the channel/catalog but it doesn't seem possible. Wondering if there is a code for this? 

Similar to Catalogs an option to sort by course code (Code A - Z or Code Z - A) would be nice and allow to adding a sequence via course code. 

And please consider adding a filter in the Channel widget for Item type (Course and learning plans, Only Courses or only Learning plans) as well as a filter on item status (not started, in progress and completed) and enrollment priority attribute (Mandatory, Required, Recommended, other)  like in the My Courses and Learning plan widget.

That would give the flexibility to configure the channels content to best support various learning journeys.