So I don't know if you've done printing before but I'm assuming not, because if you had you'd know that having print runs allow for unique keys (i.e. a unique page for every single copy) causes a huge number of practical problems depending on how it's implemented, ranging from significantly increased printing expenses through to skyrocketing labour costs. For large print runs like the Lancer core rulebook this is simply not a practical proposition.
In any case I am not here to argue the toss as to whether Massif should have taken a different strategy. For one, it is remarkably condescending for anyone to use hindsight to say "you should have done it differently" without understanding the constraints they were under or the practicalities of the printing process. For two, it's unproductive to say "you should have done it differently", because this is how they did it and it worked up until encountering the problem (which it's itch's fault, and needs to be resolved by itch). If the solution you're proposing is "don't use itch's services because they're unreliable and don't function as you would expect" that is certainly a solution, but not a good one from the perspective of itch or the creators who publish here.