Perhaps any any type of universalism needs an escape clause, such as "If a majority of votes in the (house that uses universalism) have less than a majority of current voters participating, in the first (time between elections) then the Constitutional Convention shall resume" or something to that effect.
Is there any chance of that not happening? Even if we interpret current voters to be only those who voted in the last election as well as are excluded by virtue of membership in the 15-member upper house, we're talking about 45-50 voters. Considering that we're taking out most of the more active members who would likely be in the upper house, a majority would need 22-25 people. Very few if any votes would achieve that.