I mean, even on the most basic issues, this is impossible to construct; how would the gun waving tea partiers in the US be expected to cohabitate with the Australian Liberals, who literally ban gun owners from joining their party, in a center right coalition. Or even the hilarious idea of an alliance between the Republicans and the Tories. I also doubt you could successfully unite all Sunni Muslims, Zionists, Indigenous peoples, and various sectarian interests into respective political groups.
What would happen (well aside from the whole thing collapsing in about twenty minutes) would be a situation similar to India - an endless series of horse-trading before, during and after elections. Entire political systems would put themselves up to the highest bidder - we'll support your nominee if our favoured caste gets X cash. There would be of course the basic division between the global north and south, one favouring redistribution, the other favouring the status quo - we don't really know what sort of power this new hypothetical chamber has, so I'm assuming the organisation will set it itself.
A PR system with any threshold would be a disaster btw - 2% of 6billion props would be a huge number. It would be like that election in Russia where over half the votes were for Sub threshold parties.
