Randomization in Pseudonym Pairs is trivial if a random seed can be generated. How to do that is something that can be perfected. But to demo the system, what is in test net implementation is good enough. My priority was producing a working system first, and perfecting perfectly solvable issues once that was done. To avoid getting stuck and spend all eternity on something that could have been developed at a later stage.

Consensus-by-bet as a way to agree on a random number

Voting for a number might be an approach. Any person can suggest a random number. People then just vote a bit like Vlad Zamfir’s Casper, and converge on one number...

Or even better, each persons address is the random number. And people then vote to converge on a person they, as a herd, select somewhat randomly.

If 10% collude and try and steer that... well. Not sure they can.