Nitrogen is important, but you're misunderstanding the table you link to: unless you're composting saw dust, paper or pure bark, you're not going to need to add nitrogen to have a well-functioning compost.
> Don't pee on your plants. It can chemically burn some of them. Not to mention peeing on your lettuce is just gross.
Come on, I'm obviously not advising peeing on the leaves directly, but you shouldn't water the leaves directly either.
> My compost is for dealing with kitchen waste: veggie and fruit scraps, coffee grounds etc. It it so nitrogen rich that I need to add leaves to it regularly to keep the C/N ratio where it needs to be or it goes "sour".
And this is exactly why I say people obsess with C/N ratio too much when 90% of the issues people face is caused by a poor water/Oxygen ratio instead, compost “going sour” is almost always due lack of oxygen (which is very common when you put stuff that's very moist and you don't shuffle your compost often enough). Adding leaves is indeed a good solution to this problem, but as it's not carbon-related it can be solved by other means (just by oxygenating the compost).