Usually the files in KoboRoot.tgz of the mark 3, 4, and 5 FW update packages are identical. In FW 3.5.0, which is available only for mark 4 and 5, the file nickel is different. For the modification for bad eyes patch I used the files of the mark 5 package. I don't think it will do any harm, if you have the files from the mark 4 update package on your reader and use the mark 5 nickel. (I think this is what I have on my reader currently.) But I do not know for sure. Anyway, I uploaded a version that contains the mark 4 nickel at
this post.