For example for the "First Dawn Headquarters" it boosts global chance of producing double yields by %1, but how about it also saying something like (Currently +4%) or something like that
This is already in the game. When you open the Game History tab in Citadel, you will see a summary of all numerical upgrades on the left side of the panel.
I can't believe this isn't higher!
If you don't want it in its own tab, maybe integrate it into the Recipe-tab and just put global modifiers on top and per recipe next to each one.