What were the tasks and what are the error messages? Errors are of varying significance. If you are using Version 6.0.7., some of them are (in my opinion) not errors at all, but information about issues that Eraser will inevitably encounter; these 'errors' have (correctly, I believe) been downgraded to warnings or information in the development builds of the program.
Of course all file recovery programs are not the same. But the file systems they deal with, and the methods used to store data within those file systems, are always the same. There is, therefore, a limited (and known) number of places any program can look to find deleted data, just as there is a limited number of things a program like Eraser can do to erase data, deleted or otherwise.
I have used a number of file recovery programs over the years, and I have never been able to recover a file explicitly erased by either Eraser 5 or Eraser 6. Is that a 100% guarantee that an erased file will never be recovered? Of course not; there are no 100% guarantees in this world. But all the documentation I have read indicates that the techniques used by Eraser put erased data beyond recovery for all but a handful of particularly well-resourced agencies, and perhaps not even for them.If you are an adversary of such an agency, I'd guess you'd want to use something other than an open source program to protect your data. For ordinary citizens, who might want to make sure, for example, that none of their private data still resides on a computer they want to dispose of, Eraser, particularly when used in combination with other measures, significantly reduces the change that such data will be compromised.