When I downloaded the files again, but from another source, I didn't get the error. I don't intend to use my transfer-BW on MEGA to try again, and see if it was just a fluke.
Which brings me to this, after comparing the files of v1.0.25 vs. v1.0.38 and v1.9.24 ext. vs. v1.11.16 that are linked to in the OP: It seems like "v1.0.25 Voice Effect Update" was just a milestone, and not a different branch/edition of Week 1, since after comparing them by content, I don't see much difference in size and files. This is compared to Week 2 v1.9.24 extended vs. v1.11.16, where it is clear that "extended" edition has some files that not present in the newer version.
Could anyone confirm this regarding Week 1?