I agree with @Shirley, It (slides and grade) does sound weird. BUT I know you can do it in Captivate and I suspect you can do it in Lectora. Downloading the zip doesn't necessarily provide access to the package settings.
@Arthur you don't have to compare interactions but it might help. And...if it comes down to it, one user insists they've completed and you believe them, override the activity completion setting and move on. I dug around in a captivate zip and found this:
"contentSettings":{"global":{"branchAware":false},"toc":{"enabled":false},"playbar":{"enabled":false,"cc":true,"playPause":true,"back":true,"forward":true,"rewind":true,"close":true,"mute":true,"progressBar":true}},"contentReporting":{"CCCriteria":"view","CCData":{"viewDataIsPercent":true,"viewData":100},"SCCriteria":"view","SCData":{"viewDataIsPercent":true,"viewData":100}
at the bottom of a file called project.txt. I looked at a couple other zip packages, they also have the same file in them. It looks like you might be able to modify the view percentage by fiddling with this (or you could destroy everything). I've made adjustments to packages a few times by copying the file in questions and pasting it in a non-zip folder. Make the changes, save (I would save two copies of the file, just in case, or maybe make a spare copy of the unadulterated zip), replace the file in the zip with the edited file. Update the zip in Moodle. It could work. But it's risky. And this is captivate. If the project is in a different software, it will likely have a different file name and you might have to dig.
Just for emphasis--I don't recommend that last option. I'm just saying you can, not should. I've done things like it before, with some relative success but it could mess up everything and you don't have the actual source files (well, you may have them but not the software to use them. Do you know what software was used? Does it still exist? Could you get a license?