Nope, the project info system is, IMHO, quite disabled. Your are correct that the 14 default entries cannot be deleted or renamed.
While the Help system says that you can add any number of new entries, I seem to recall hearing that the number was actually limited. Perhaps there is a way for you to combine some of your fields into a single entry. For instance if you are entering addresses, enter everything into a single field instead of one filed for name, one for street address, another for city, etc. Perhaps then you can fit everything.
HTH
Erich
AC 19 6006 & AC 20
Mac OS 10.11.5
15" Retina MacBook Pro 2.6
27" iMac Retina 5K