As we answer this question, let us first note that there are five authors of this paper. Judging by their names, the first two authors are both female, the last two are male and the middle author’s name does not make their sex immediately obvious. Since the lead author is female, if we refer to one author only, we should use female pronouns.
In academic papers, authors typically give two types of evidence to show that they have sufficiently covered the subject matter. One type of evidence is found in the “Works Cited” section of the paper. Here, authors show all the works that they have consulted, hoping to prove that they have looked at everything that is relevant to their topic. The “Works Cited” section of this paper cites 159 sources. A second type of evidence is found in the literature review section of the paper. Here, the authors work methodically through sources on the nature of acculturation. Then they work through sources that have studied various ways in which acculturation affects Latinos’ health outcomes. Because they have consulted sources on the meaning of acculturation and on its impact, it seems to me that they have proven that they have covered the subject matter sufficiently.
One further thing to note is that a paper like this is peer-reviewed. Peer reviewers are experts in the field and therefore have much more knowledge of that field than you or I do. If the author had failed to include any important sources or to discuss any relevant aspect of the question, reviewers would have pointed out the failure. This, too, ensures me that the subject matter has been sufficiently covered.