I'm trying to build a character but the first major cornerstone of the build is the "Helpful" racial trait for halflings that seems to be missing. I did some google searches, the trait doesn't seem to be illegal or errata'd out for any reason. Am I missing something?
Archives of Nethys says it's on page 30 of Halflings of Golarion. Your comment indicates you already found it, but for others with a similar question, you can add sources in PCGen through the Sources menu option at the top of the window. You can select Load Sources to choose a commonly-used set of set of sources (such as Pathfinder Core or Pathfinder Society) or choose Select Sources to individually use or ignore individual books on a case-by-case basis.
As an aside, while I normally prefer d20PFSRD, the Archives are a good place to go for building Pathfinder Society characters, as they mark PFS-Legal options plainly without you needing to go check Additional Resources for every trait and feat you select. They also tend to be more specific with their citations, so you can find the book a particular option is from more easily.