Yeah, I was too lazy to make a map, so I thought putting people on Mars and forcing them to start everything over was a clever idea... That and I read the General series and thought it was cool.
Well, we spend over 20 pages discussing how it could work, so I think it's fair.
I mean, how advanced do you think the Nerinese as the whole would be? What would be a key technology of each fields? What fields would be advanced to which points?
Anything that can be achieved without electronics.
Electronics, even including spare parts that were eventually used, was irreversibly damaged by persistent black-out scenario. However, it was only a matter of time before they realised that many underlying scientific principles still work, and things can be build and operated, including steam, combustion engines etc. you only need to dumb down entire process to be as manual as possible, without no electronics to guide it. This was an issue, especially when they were far in the future, and were reliant on advanced / hi-tech electronics even more than we are.
Many things fell backward, considering everything needed a manual labour, and dumb down processes in manufacturing.
I feel, WW1 era, early 20th century, works well as indicator of progress, where automation didn't exist, and everything required a lot of manual labour.
Metallurgy probably regressed a lot. They basically ended up manufacturing steel in the way we did back in early 1900
They have idea of chemical or biological processes than we had back in the day, but they are limited by everything working manually. Crude, simple, effective, is probably the motto.
There is even a good explanation why they have 1st world war weapons. It requires industrialisation and it is no cottage industry, but there is no electronic, no advanced processes, mechanic is simple. Actually, they ended up using weapons that they are certain they will go bang once they pull the trigger. There was a long era of peace, and they didn't feel the need to fight any major war, so there wasn't any need to force any advancement.
They don't use solar panels, because they can't really make those, but they certainly know how to make a steam or water turbine. Nuclear power is not worthwhile, because you can't operate it safely considering the general unreliability of ... what is roughly 50's level of electronics which simply isn't around it setting, radioactivity is still deadly, and eventually, it was forgotten
In general, once first and second generation died out, they were mostly ended up with people who were educated in the simplified processes, and they once more had to reinvent things. There was probably a lot of focus in educating future engineers in simplified, start forward, electronic independent processes. I suggest many things are actually know, re-invented early on, population spends a lot of time building an infrastructure non reliant on electronics, but run into hard limit what can be built due to no control over certain mechanics.
Then add Age of Magic somewhere later on, where magic is actually proven to exist, and warding proving to work.
But they again stuck because they can't mass produce mages, so they still spend lot of time with mage independent techbase which isn't very advanced, and something comes to use only after certain area have certain number of mages.
Then they start building civilization around mages which worked, but was cut short by war (and plague)
Now, war is over, they need to deal with many inevitable post-war issues, but I would assume once they figure that out and after few magical-technological breakouts, overall technological levels would experience massive boost.
Main story (stories) would be centred (dated) around this time of uncertainty.