Jedec defines ~3 quality classes, which exist across all speeds.
5600 CL46, which is the most common is the middle one. 5600 CL40 is still Jedec, just the higher grade of 5600. 5600 CL50 would be the lower grade.
For 4800 the usual config is CL40, the higher grade would be CL36.
Modules should stay in their same “quality grade” across the frequencies. Which is why my 5600 CL40 modules also spec 4800 CL36 and 3600 CL 26.