This paper is a synthesis of 137 other papers, which is more than I can chew in one work day while still remaining gainfully employed.
But I just speed-read it, and I didn't find anywhere that it unequivocally states that the tendency for immigrant communities to self-police undocumented immigrants, resulting in lower rates of reported crime, has been compensated for. It seems I would have to read dozens of other papers to find out. Nor can I find any place where it unequivocally states whether we are talking about absolute or per capita numbers of criminal acts.
So I'm going to go with the headline, which is not especially meaningful since it elides any difference between per capita and absolute numbers.
All that said: the headline conforms with my own experiences dealing with immigrant communities, both legal and illegal. People who have the gumption to move to another country are well above average in a number of ways, and hard-working, capable people rarely need to resort to crime to achieve their goals. People who are too stupid, lazy or soft to "vote with their feet" are more likely to commit crime.