Would "understanding" this fact make it more difficult to keep the Law?
I believe this made it easier to keep the Law, because you understood it better and you would be less legalistic about it. Those who understood this, understood how they could remain in fellowship with God even if keeping the Law was impossible; we see this in particular in the writings of the prophets during the exile.
And did this in turn cause the pious Jew to make it something (their own) which could be kept?
I believe the modifications made by the pious Jews were not so much to make it something which could be kept, as much as to shape it so it looked more like what they wanted.
Yes I agree.
What I was pointing too in my first question is being "under" a legal code which you know cannot restore the breach, compared to us today, who are witnesses to a living Gospel with a real power to save and restore. The mystery revealed and a binding law taken out of the way.
We know...Abraham long for the day of Christ....Moses sought a prophet greater than himself...David looked for one greater to sit upon his throne..and so on
We are richly blessed to be given the Prophetical Visions of the past and future.
We have the whole Book.
Lets hope we don’t do as you say:
...as much as to shape it so it looked more like what they wanted.