Nah, Zeta Halo was definitely made by the Forerunners, I've seen that conversation come up, I can't remember the exact wording but I'm fairly sure that she was simply saying there's things on Zeta Halo which are older than the Forerunners but not that Zeta Halo is older than the Forerunners which makes sense since Zeta Halo acts as a sort of prison for other species.
Nope, after the last artifact the final log definitely said that the ring predates the forerunners.
Ok nvm, it said runes, not rings. My bad
Makes ya wonder what else is trapped down there...
Flood Spore 👀
But they could be other species imprisoned there too.