Unfortunately, this additional information does not actually clarify the matter. Apparently there are two distinct "single subject rules", one pertaining to legislation, another to ballot initiatives. To add to the confusion, the legislative rule is part of the state constitution, and the rule that proposed amendments to that constitution, properly identified as the separate vote requirement, is often referred to as a "single subject rule".

Regardless of all that, since the legislation being voted on relates to the 'single subject' of proposed constitutional amendments, I can't see it being an issue. As long as the ballot allows each proposed amendment to be voted on separately, it doesn't matter if the legislation contains multiple proposals any more than it does if several amendment proposals appear on the same ballot, as long as they are not bound together so that they must all be affirmed or rejected as a group.