It appears the 2023 version of that form is majorly disfunctional. Not only does it not do the calculations you are expecting, none of the hyperlinks in it work either. If you look at any of the previous years' versions of that same form (they are on the website), they work properly, so it looks like whoever at RQ did the modifications for the 2023 version didn't do a very good job! Let them know that this form is not working.
FYI, there's a reason there's a password on these things. They don't want you fiddling with it. Even though there are tools that can unlock them, there are possible legal ramifications to do so. I doubt the Revenue Quebec people would look kindly on this.
(side note: the PageMaker reference looks like it was originally created back in 1999 in PageMaker, and they must have been simply patching and modifying the parts that changed since then: if you look at the non-fillable versions, they are definitey based on InDesign documents.)
Update: I think they figured it out: the English form now downloads correctly. Try again!