Three bodies of scholarship read this Regulation in incompatible ways, and each of them is arguing in good faith from the same documents.
The reformist reading, which was the standard one for well over a century, treats 1829 as a milestone of emancipation: a cruel practice abolished, and Indian and British reformers rightly credited with abolishing it. It has the advantage of taking the deaths seriously as deaths.
A Hindu nationalist reading treats the affair as a case of colonial overreach, in which an aberrant and localised practice was magnified into a defining feature of Hinduism in order to establish that the tradition needed governing. This reading is right that the practice was not enjoined by any general scriptural requirement, and its critics answer that minimising the incidence has become a way of avoiding the question of the deaths.
A feminist and postcolonial reading, of which Lata Mani is the standard statement, points out what both of the others share. The colonial debate was conducted over the authority of scripture, the definition of tradition and the proper role of the state, and the women who burned appear in it mainly as the ground on which men argued. Gayatri Chakravorty Spivak framed the same point as white men saving brown women from brown men, with the women themselves given no position from which to be heard.
The atlas does not adjudicate between these. What it can say is that they disagree about what the reform was, not about whether it happened.