Now, the caveats obviously apply that these inscriptions may not actually be in Latin and the language Severian speaks is likely quite different from modern English, but still, there's something strange about it. I'm not gonna pretend to be fluent in Latin but as far as I can tell his translations do indeed seem much more literally accurate than Valeria's. She says 'Lux dei vitae viam monstrat' means 'The beam of the New Sun lights the way of life,' which is strange because lux dei means something more like 'the light of god' than 'the beam of the new sun,' and she says 'Felicibus brevis, miseris hora longa' means 'Men wait long for happiness' when it translates more directly as something like 'happiness is short, sadness is long.' I'm basing these translations off this post 12 years ago by a guy called Jack. However, something interesting is that her translations from Latin to English are not very good (or at least not very literal). Once Severial goes indoors and talks to Valeria, she mentions ancient mottos which some Urth readers noticed are similar to Latin mottos written on real sundials. So I'm leaning towards the interpretation that they actually are just regular sundials, though the satellite idea is pretty cool to consider. Some readers have interpreted these as actually being defunct satellite dishes, which would explain their tilt, but I'm not sure about this because satellite dishes have a concave shape while sundials are usually very flat, so I don't think the same object could function as both. Severian describes the Atrium as being full of sundials which are tilted at strange angles. Some people have suggested that it is a location similar to the 'Last House' from later in the series, which is somewhat separate from normal space/time and can only be arrived at by following specific directions.

First of all, Severian only enters the Atrium through a maze of tunnels underground, and is unable to find it any other way, which is strange because it should be visible from some of the towers in the Citadel. This is a very confusing part of Book of the New Sun and I've heard some contradictory things on this subject.

Book of the new sun