It's a time where there's been a surge in scientific development, so it would make sense to me anyway if the application of the scientific development overshadowed the actual science of what was being developed. Also for non-scientifc people, a lot of scientific terms sound similar, or are hard to wrap your head around. So their understanding of stuff isn't very good.
Ultimately though, Shin-Ra is a company that cares about the results. So so long as they can get the results they want how ever often they want, the information that was the basis for the results in the first place isn't that important. So if some information about where something was found, or where something is stored, or if something could cause mutations goes missing, no one is going to miss it if it doesn't have something to do with producing whatever result you want.
It's also wroth considering that nobody misses information if they didn't know it existed in the first place, or if they don't have a reason to go looking for it. IE, Sephiroth has no reason to think that Jenova was not just a case of his mom dieing in childbirth, so he has no reason to go looking up her records. So he wouldn't even know if the records looked "off" or were missing in the first place.