"severe lesson" is correct and usable in written English.
For example, "The student had to learn a severe lesson about responsibility."
I think it's a very severe lesson on complacency".
America went from being considered indestructible to being a nation that had to be taught a severe lesson.
England's finest are urged on to the training ground, following "a severe lesson in the arts of association football".
The fairy then "allowed the puppet to cry and to roar for a good half hour over his nose … This she did to give him a severe lesson, and to correct him of the disgraceful fault of telling lies — the most disgraceful fault that a boy can have".
THOSE EUROPEAN TELEPHONE MONOPOLIES are about to get a sudden, severe lesson in price competition.
They will be met with fire and fury like the world has never seen," Trump warned Tuesday after North Korean Foreign Minister Ri Yong Ho said his country "is ready to teach the U.S. a severe lesson with its strategic nuclear force".
Even as the damage appears severe, lessons from 2002 translated into more robust flood prevention in much of the region.
Although it's far from China's northern provinces where renewable energy integration issues are the most severe, the lessons learned from the project will be applicable anywhere in China.
All the more reason to be severe in assessing lessons learned.
By way of voice lessons, wearing severe suits and her own aggression, Margaret Thatcher mastered it (the verb seems appropriate).
Dark Souls and its sequel are great examples, where the initial contact can be severe, but you learn lessons.
