FYI. Here are the amendments (according to an Amazon commenter):
1. Term limits, including for justices.
2. Repealing Amendment 17 and returning the election of senators to state legislatures
3. A congressional supermajority to override Supreme Court decisions (overruling what could be a stacked court)
4. Spending limit based on GDP
5. Taxation capped at 15%
6. Limiting the commerce clause, and strengthening private property rights
7. Power of states to override a federal statute by a three-fifths vote.
In my opinion this would massively change the US fracturing it into something closer to the European Union than it is right now. Also the idea if capping taxation at a percentage would mean that we couldn't have fought WWII (or at least not without probably immediately going bankrupt). A congressional majority being able to overturn the supreme court completely rewrites the balance of powers as well.
I understand where a lot of those are coming from, but as you said, this would massively change the dynamic of the country in a brutal way, especially without attacking massive underlying problems in Congress. The taxation cap is just... that would be wholly detrimental to practically every system across the country.