1. The asymmetric adjustment of weights in the save file is only valid as long as the election is on a date other than 1st of month - this is because normal game adjustments to rels take place just before the election and, at least for adjusted rels, the matrix is reset to symmetrical. So I assume your Iroquois election was on another date.
2. Your result seems to confirm that the more electors there are, the more 'likely' it is that there are low-weighted electors. We know it isn't as simple as a fixed relationship between no. electors and weights, but still....
3. Your Iroquois save looks very like my KNI 1705 results that I started off with right at the beginning. Since the discovery of the L3 phenomenon I haven't touched this game. You can look back at the detailed results. In summary, there were 7 electors, KNI was right on the margin of being able to win at all, and the bonus was around 1200. I did not explicitly test for elector weights, but there was no prima facie evidence that any of the electors were weighted. I have not tried to make an L3 invariant save.
4. Might the base bonus be 1200, less some amount for the each low-weighted elector? Or something like this?
5. I'm not surprised that you could not find any other save file factors that relate in any simple way to the results, I have found the same. I still wonder if alliances or being at war have some effect, but if so, it's not straightforward.
6. No news from me as I am in the middle of computer upgrades and have no EU installed at the moment. And EU2 is about to be released here, so I may move over to that. It looks like you are playing both. Do you have them installed on the same machine and if so, do they coexist happily? If so I'll reinstall it and may try some more tests.
6. But, I admit to losing confidence. I don't really have enough faith in Paradox - we may be looking at a designed, if weird, election system, or we may be looking at the side effects of bugs. I do believe they are desperate to protect the AI from human players decoding all their AI systems, both by allowing large random effects in the game (whether deliberate or bug related) and by disinformation on the forum. I'm afraid I think they would be happiest if there is no reproducible election system, so I do fear that I (we) have been wasting my time.