The Confederate Constitution is available on-line, and incorporates a lot of the U.S. Constitution. The Bill of Rights is incorporated bodily into the CSA Constitution. There are changes that appealed to sectional interests, including limitations on tariffs and a prohibition on spending to facilitate commerce (meaning roads, railroads, and so on). And there were provisions that locked slavery into place. Article I, Section 9 (4) said "No bill of attainder, ex post facto law, or law denying or impairing the right of property in negro slaves shall be passed." Not only is slavery enshrined up there with no bills of attainder or ex post facto laws, not only is Congress forbidden to interfere with it, but it's described as a right. Wrap your heads around that.
Still, they'd had 73 years of experience under the Constitution, and they saw a few things that needed tweaking, and a few they even got right.
Article I, Section 7 (2) The President may approve any appropriation and disapprove any other appropriation in the same bill. In such case he shall, in signing the bill, designate the appropriations disapproved; and shall return a copy of such appropriations, with his objections, to the House in which the bill shall have originated; and the same proceedings shall then be had as in case of other bills disapproved by the President.The President can veto selected appropriations, which Congress can then override. This is called a line-item veto, and Presidents since Eisenhower have called for it. (The issue hardly arose before Roosevelt. Roosevelt oversaw the huge increase in spending between the Depression and World War II, and Truman, as his successor, carried on Roosevelt's policies. By post-1945 standards, budgets before 1933 were miniscule)
Article I, Section 9 (20) Every law, or resolution having the force of law, shall relate to but one subject, and that shall be expressed in the title.This would eliminate the practice of passing "Omnibus" bills that cover a plethora of subjects, and seriously crimp the practice of attaching riders to bills.
Article V Section I. (I) Upon the demand of any three States, legally assembled in their several conventions, the Congress shall summon a convention of all the States, to take into consideration such amendments to the Constitution as the said States shall concur in suggesting at the time when the said demand is made; and should any of the proposed amendments to the Constitution be agreed on by the said convention, voting by States, and the same be ratified by the Legislatures of two- thirds of the several States, or by conventions in two-thirds thereof, as the one or the other mode of ratification may be proposed by the general convention, they shall thenceforward form a part of this Constitution.This measure departs from our own Constitution in several ways. First, there is no mechanism for Congress to propose amendments, although with only three states required to call a convention, it seems likely that Congress might be able to persuade states to propose what it wanted.
It eliminates the worst concern about calling a Constitutional Convention. Under the U.S. Constitution, there are absolutely no restrictions on what a Convention can consider. The process is spelled out more explicitly here. The Convention is limited to the amendments proposed by the states, and has the power to decide whether the amendments are to be ratified by legislative act or state conventions.
The most important change is that only three states need concur to launch a convention. Given that the Confederacy had only thirteen stars on its flag (one for each seceded state, plus pre-approved stars for Missouri and Kentucky), this measure effectively means that about a quarter of the states can call a convention (as opposed to two thirds under the U.S. Constitution). Only two-thirds of the states (as opposed to three fourths) are needed to ratify. The reason for the differing limits in the U.S. Constitution is to prevent the same states that called for an amendment from ratifying it as well.
Both liberals and conservatives freak out at the idea of calling a Constitutional Convention, solid evidence that it's a great idea. Look at what happened the last time we had a convention consider modifying the basic law of the land, they warn. We got a whole new Constitution. Yes indeed, look. The new Constitution was approved by Congress and sent to the States. It took nine states to ratify, a process that took two years and generated intense debate. It's not like the Constitutional Convention simply rolled out a new law on its own and said "obey." That requirement that three fourths of the states ratify any proposed amendment is a very high bar.
So they did indeed get this one - mostly - right. Having Congress able to propose amendments is still a good idea. Three states is setting the bar a bit too low, but ten or fifteen is reasonable. In fact, let's bypass conventions altogether. If ten states pass resolutions calling for an amendment, the amendment goes directly to the states for voting. It will still take three fourths of the states to pass.