Writing skills are best learned through practice, critique, and revision.

Curriculum is a waste, in my opinion – that is, listening to generalizations about how to write something other than the task at hand. Only the actual words on the page are worth discussing. Not rules.

Maybe courses would be worthwhile if they entail a lot of hands-on interaction with a brutally honest, pragmatic instructor.

What your team would really learn from, I suspect, is watching someone perform surgery on their copy, pausing to explain why the guts are being ripped out here, why the sutures are stitched up in such and such a manner there, etc.

Consider hiring someone to workshop in person with your team. No prearranged abstract curriculum. Just critique.