I'll be honest in that I found this article (Challenges in Defining and Building Community within the Curatorial: The Pacific Standard Time, LA/LA Edition by Bill Kelley Jr.) to be poorly written and somewhat confusing. It reads to me as an expression of a variety of dissatisfactions and an inability to articulate an adequate response to previous/ongoing failures. It might be helpful to back up and remember what community engagement is about for Kelley and possibly others--at least as far as I can tell. That the major cultural institutions which archive and maintain historical memory disproportionally serve and recognize "Western" history (and by this I take him to mean European/American) and dominating sociological groups (whether its white people, rich people, both--unclear) in their--the institution's--societal function. On these terms I would say that Kelley is calling for a decolonization of cultural institutions in general. With this as his end, he takes up community engagement, curatorial practices, and art historical research as means. He lays out a variety of things he sees worth taking up, for instance on the point of community engagement:
“The importance of community-organizing efforts within a framework that emphasizes a particular community cannot be understated and the lack of that framework makes this kind of institutional/curatorial effort challenging.”
And he clarifies what community organizing or engagement means for him:
"For the sake of reference, the more the community is asked to be involved, the more the platform moves towards direct action, the greater the focus is geared towards questioning power relations."
Another reference which I'll tack on (as I think it resonates with Kelley's perspective) comes from the artist collective "Ultra-Red" who was featured in the SAIC exhibition of Kelley's project Talking to Action: Art, Pedagogy and Activism in the Americas:
“If we understand organizing as the formal practices that build relationships out of which people compose an analysis and strategic actions, how might art contribute to and challenge those very processes? How might those processes already constitute aesthetic forms?” <
(Links to an external site.)

This brings up the curatorial aspect of Kelley's project--how does an aesthetic education activate or mobilize political or community-oriented activity? This, as far as I can tell, goes unanswered. But his reference of Gamboa's Spray Paint LACMA might be a hint. Finally on the point of art history, as Simone mentioned above:
"Setting the archival record straight isn’t only the job of some obscure militant research project, it’s the fundamental job of art history. [...]
I would beg to differ on this, I would say that the fundamental task of art history is to clarify the historical developments of freedom as expressed through cultural artifacts. But regardless, this above quote brings out what I mentioned above as what Kelley understands as his role in the field of art history.