[2021] I'm not sure if anyone has already decoded them, but here's what the alien language in the city translates to

Arat Prime is locked down. Launch Initiated. Proceed to nearest shelter.

Emergency Action is in effect. Violations will result in immediate punishment.

Hostile forces are inbound. Proceed to your nearest shelter.

Manual Override Initiated! (Thanks u/seeker-ace !)

(These are the ones I have come across. There may be more. I will update this post if I find more!)