Is there a way and ordinary person can verify these codes? Maybe a simpler and non complicated way?
Unfortunately, everyone who could not read the code and check every line in it and understand its dimensions must trust in other people, so even if the code is open source, if you do not find enough people who read it, do not use it.
Hackers always have an advantage as they look for weaknesses in the system that others cannot discover, and it is more difficult for the developing team because they fight in the dark.