No that's alright, I just wanted to know from what perspective you're asking the question so I can give a meaningful answer. I think that wikipedia segment is very poorly written and not true at all. I know of no RFC mod (including the base mod) where tech rates change over time or due to some event. You already found where the modifiers are (Modifiers.py) and they work pretty straightforwardly: each civ has its own modifier in a variety of categories that affects their performance in that area, usually percentage based, reflecting how well these civs were doing in those areas historically. They are static throughout the game. When choosing them, I usually have outcomes in mind instead of looking at the modifiers directly: for instance, China has historically been one of the most advanced civilisations in history for long periods of time, but their research modifier is fairly bad to account for the fact that they already benefit from an early start and good terrain.
If you have more specific questions let me know, but your initial question seems to come from a wrong assumption due to the misleading wiki article.