Oh. Right. Ha. I haven't looked at that bit of code for a long time.
The provided character manager tool is intentionally simple, so it can serve as an easy to understand demo tool as well as providing basic functionality to test things like character parts and facegen morphs. Basically, it pays no attention to the extra information in the facegen.dat file.
The limit info you attempted to add is fine as is, there's just nothing using it. So, for now, I wouldn't worry too much about things looking extreme in the character manager. When you build your character creation GUI, you can take all the added limits/etc into account to prevent ugly or extreme morphing.
To see how to make your character creation GUI load the information you need from the facegen.dat file, look at the HJREF character creation GUI. Specifically, look at HJCCSFeaturesPanelClassMethods, lines 65 through 92. That is the code that parses the keywords. Then just follow the function calls, AddFacegenSlider() is called there with the keywords passed in. That function is on line 119 of the same file.