Actually, nowhere do they say those memorials are only cloudstriders. Given it's called the "hall of heroes" its likely there are non cloudstriders kept there. Remember anyone can be a hero, not just cloudstriders. Also we see Osiris place his ghost in there, which if it was for cloudstriders only, then he shouldn't have been allowed. There is a mural with 16 cloudstriders on Neomuna. So that 160 years of Neomuni history. Rohan was like 8 years old at the time of his death. So the cloudstriders have likely been around for 168 years. Given the the Neomuna tech is only slightly more advanced than late golden age tech seen on titan. It's likely the colony existed for about 20-40 years before the 1st cloudstrider. So the colony is likely 190-230 years old. Based on lore surrounding the speaker, we can estimate that the city age has lasted 50-60 years. So this would mean the dark age lasted 130-170 years. We also know that the traveler tripled human lifespan, meaning the golden age lasted atleast 300-400 years. In other words, the traveler has been in Sol system for about 600 years. This would make sense since we know that Mithrax was born after the whirlwind (making him roughly 600 years old) and Erimis was born pre whirlwind, making her 800-1000 years old. Also keep in mind, based off early golden age tech seen the the cosmodrome as well as the original openingcut scene. The discovery of the traveler likely took place between 2000-2010.