User blog comment:GrandMethuselah67/World-5 Loresheet: The Federal Kingdom of Sol/@comment-4867780-20151108074436/@comment-26322734-20151108184633

Yeah, World-5 isn't supposed to be the most realistic of my 'verses. But there's an in-universe answer to your questions.

Due to both humans and the Outer Flood originating from the Farseekers, both species' ability to construct language, at the basest neurological level, is ultimately a variation or iteration of Farseeker runes. Therefore, the language of the Outer Flood and all human languages are derived from Farseeker language; this was so that the Farseekers could easily communicate with the humans or the Outer Flood if they wanted to conduct another experiment, say, thousands of years into the future.

So the humans are able to reverse-engineer some of the Outer Flood's technology because they have some semblance of an intrinsic understanding of their language, as it follows the same fundamental rules of all of their languages. As for technology differences, they're not necessarily, say, taking an Outer Flood laser canon and immediately learning how to use it. They're breaking it apart and creating schematics based on what they do know (meaning they don't know the full applications of much of the technology they're making schematics of). A lot of the scientists working on this stuff have abilities like Psychometry or some other form of extrasensory perception.