the top two stakeholders can not even come close to electing even a single witness at all, much less all witnesses.

Their two votes alone get someone very close to the number 20 spot by themselves and I think that many of those other votes are only there because they already received a vote from a top stakeholder. Impossible to prove yes, but intuitively seems very likely. In very general terms it is plain to see that under the current system we could have one massive account selecting all 20 witnesses. Dropping vote limits from 30 down to 5 would make that less likely which should be our goal.

On top of that we should probably have some kind of vote decay as well, where a vote expires after a year or so, that way we don't have dead votes/dead accounts keeping people in that really have no business being there.

That is another aspect that needs exploring.