Chris, just as in photography, attention to detail in precision SV cooking is important for successful results. I don't think you took the correct steps with your Catastrophe and here's why.
First, i don't think you had sufficient information to make the correct decision and guessing can be harmful to your health. Details are important.
I plan and execute all my cooking as if i am working with a highly contaminated product. Under normal SV cooking techniques roast-sized pieces of meat don't present a food bourn illness hazard when cooked above 130ᴼF / 54.4ᴼC to make your food safe. That's called Pasteurization.
You don't reveal the type of roasts you are cooking, nor their thickness, thus it's not possible to recommend any cooking time adjustments to help you. The weight doesn't matter when considering cooking times, but thickness always does. That's because SV cooking occurs at significantly lower temperatures than in conventional cooking and heat diffusion is much slower. That gives us somewhat of a race as we cook to kill off enough harmful pathogens in the meat before they can multiply to a harmful level. This race is only ever 4 hours long. You need to get the core of the meat above 130ᴼF / 54.4ᴼF in 4 hours. If you have the danger of harmful pathogens producing heat-resistant spores in the product that can make you very ill. That's why i limit my SV cooking to pieces of meat no thicker than about 3-inches. Any thicker and you risk losing the race.
In your Catastrophe you likely achieved Pasteurization, but not knowing how thick the roast we don't know when. Your concern was, or should have been, - how long did the roast rest at a temperature below 130ᴼF / 54.4ᴼF? And if it did at all. You might have answered that question if you measured the roast's core temperature at the 6 hour point after your circulator was turned off. I would have disposed of the roast if the core temperature was significantly below 130ᴼF / 54.4ᴼF. Too risky, particularly if was fabricated or roast that had a bone removed and retied instead of one solid piece.
How far below that temperature?
Again, thickness matters. We know that heat penetrates at about 1-inch per hour. A quick calculation of the temperature gap and thickness will tell you if it's safe to proceed in order to get the core temperature back to where it needs to be.
One more thing about temperature and food safety. Those 4 hours below 130ᴼF / 54.4ᴼF are cumulative. It's the total time spent between 40ᴼF / 4.4ᴼF and 130ᴼF / 54.4ᴼF while heating or cooking and while holding for service, or when chilling before refrigerated or frozen holding.
I regret this reply is overly long, but a detailed understanding of safe SV cooking technique will keep you well.