while not an expert, here is what I think is happening.
1. The NIV module you purchased (1984) is a premium module. It is locked, and unable to be legally altered. The eSword converter will not convert it, nor will the T4 program mentioned above in the thread. I am unaware of any legal method of making any changes to it.
2. The NIV84 has legally been removed from publication by its publishers. As I understand it, it is no longer legally available (except as "used" where you might find it). This might make it impossible for eStudySource to be of any help at all. If you want to get the any version of the NIV84, your only legal option will be to go back to them. Here is the good news: they are easy to work with, and rather friendly, too. If possible, they will provide the update. If not, I think you are out of legal options to obtain it.