I happened to utilize the methods mentioned in the material in the last community i managed (VIETDOGE).
It happened post TGE. The founder may or may not have over-promised and it bit back immediately. Token launch came and went, but the disgruntled voices in the community kept rising. I took the initiative to craft message that went in the line of "We overpromised, forgive us, and we have more products on our roadmap that will deliver as promised". Sent it to Founder, he vetted then posted it. I only had to be very active, doing some damage control with core loyalists. At some point, the loyalists became the voice, quenching the flames of FUD. It was a nice experience.
I can boil it down to timing. Crises always get worse been it is not address ASAP. For me, that is the true lesson I can take from this material