The library tab is pretty, but compared to quickload, it's really kind of a redundant feature. It's a really handy way to custom organize all of your Kontakt libraries. If you haven't yet familiarized yourself with Kontak's quickload feature, try it before you do anything else. Tampering would technically violate a EULA, void technical support, and terminate the privilege to resell your license, but at the end of the day, all you're doing is building a better mousetrap for personal use. Nanjo contains: 13 notes, four velocity layer, and 154 24bit samples recorded at 48khz. If you are a single user using a legally-purchased copy of Kontakt and legally-purchased non-player libraries, whatever you do to make your libraries more convenient to load in your DAW is your business. This Kontakt library includes eight free Kontakt Instruments for free, and they are Nanga, Toy Piano, Balafon, Vibraphone, Fender Jazz Bass, Fender Rhodes, Zither, and Banjo. In other words, they don't want you cracking the software and reselling it. EULAs are designed mainly to deter library abuse on a grand scale, specifically pirating. I don't ever advocate violating a EULA, but I tend to look at EULA situations from a practical point of view.
To make a non-player library show up in the libraries tab requires tampering with the software, which is a violation of the EULA. All other non-player libraries must use the files tab or quickload feature. To have one's library included in the Kontakt libraries tab is one of the perks of licensing a library with Native instruments for the Player version.
