I am not able to comment on the contents of Fr. Powell's books because I have not read them; however, because he wrote more than two dozen books primarily on the subject of psychology and/or love and relationships, I can only wonder why anyone would want to read books on this subject by an author who was credibly accused of sexually abusing women. This is hardly the kind of person who should be sought for advice!
According to the public record, Powell, a former University professor who died in 2009, was accused of sexually abusing seven women in the 1960's and early 1970s. Several of the cases against Fr. Powell were settled by the Jesuits in 2005.
You are correct about the late Anthony DeMello, S.J. He liked to combine the teachings of various religions in his writings, which often found him straying beyond the boundaries of authentic Christianity. More detailed information about DeMello can be found here.
We need to keep the souls of these priests in our prayers!