Not being able to see the displays is a "definition" to identify severe turbulence.
When it comes to fan blad failures, the Boeing FCTM is pretty scary. It states vibration may be severe, but "it is extremely unlikely that the vibration will damage the airplane structure or critical systems". It furthermore discusses the impact on human performance and gives some advice "to find relief" like leaning forward or even... standing up. I think the main goal is to remain seated with seatbelts on. When reading this the first time I did wonder what level of vibration we are talking about and what the psychological effect would be if an FCTM needs to comfort you it will not damage the structure.
I've talked to some people who've experienced engine surges. Most of them fairly "as expected" from simulator training, but one described it as "much more violent" than the simulator.