James Madison didn’t propose 19 specific amendments; he proposed 9 in his address to Congress on June 8, 1789. His original numbering was broken down into which Article was being amended. He thought amendments should replace existing text or be inserted into the text rather than being added onto the end. So for example the bulk of what would become the Bill of Rights was simply his 4th Amendment as he thought they should all go “in article 2st 1st, section 9, between clauses 3 and 4.” A single large insert of text was to his mind a single amendment.

This is why you’ll hear various counts of how many amendments he proposed. This is because he himself grouped them differently than in their final adopted form, and at various times different paragraphs were combined or separated into different amendments during debate. Arguably what became the 1st Amendment really should have been 3 different items; freedom of religion, freedom of the press, and freedom to assemble are different rights. But Madison and later Congress grouped them together. This is why people often say he proposed 19 or 20 amendments instead of just 9.

Ultimately he proposed 9 amendments, of which most were reworked into 12 adopted by Congress. Eventually 11 of the 12 would be ratified, although one would take till 1992.

Here’s his 9 original amendments summarized.

1. Alterations to the preamble. Specifically to make clearer that all ultimate power derives from the people. This was rejected and not adopted by Congress.
2. Changes to wording in Article Two regarding the number of Representatives and how many people they could represent. If adopted this change would have capped House seat sizes at 50,000. Which would give us some 6,600 odd members in the House today had it been adopted. This one was approved by Congress, but never ratified by the States.
3. That pay-raises voted on by congress couldn’t come into effect until after the next election. This one was voted on and approved by Congress, but not ratified until 1992 when it became the 27th Amendment.
4. What would become much of the familiar Bill of Rights. Freedom of Religion, Speech, Assembly, to Bear Arms, to not Quarter Soldiers, Fair Trial, Fair Punishment, from Search, Speedy Trial, and an Enumeration of Powers. These were reworked and regrouped into different arrangements. After debate and reworking this was approved and ratified.
5. This was basically a proto-incorporation clause requiring the individual States to respect rights of conscience, press, and trial by jury. This was rejected by Congress, although under current law this functionally exists
6. This was largely what would become the 7th Amendment it offered rules to protect the civil law trial by jury, as well as guarantees for traditional common law. In the final Bill of Rights this was moved up to join the other court related amendments from part 4. This was approved and ratified.
7. further enumeration of trial protections including details on juries, and grand juries. Parts of this was worked into the eventual 5th Amendment, and was approved and ratified.
8. Further discussion of the enumeration of powers. This became the bulk of the 9th and 10th amendments. This was to be labeled Article 7. This was approved and ratified.
9. Relabeling Article 7 in the Constitution to Article 8.

Most of Madison’s proposals were accepted. Of his 9 proposed amendments 1, 5, and 9 were rejected. 1 and 9 because the rest of Congress didn’t want to edit the Constitution directly, but to append amendments to it. 5 was rejected because they didn’t want to try and force rights onto the individual states which in some cases had such rights already. The other 6 proposed amendments were reworked into 12 amendments passed by Congress and sent to the states for ratification. Proposed amendments 1 and 2 failed ratification. So when amendments 3-12 were ratified, they became the common listing we know today, amendments 1-10, with what would become the 27th amendment becoming the last of his proposals to become ratified.

Today of his proposal, most of it is in the Constitution. Outside some wording, and the constituency maximum requirements for House districts, there’s no major part of his 9 amendments that isn’t law today. There’s only 1 “missing” amendment, not 9.

Edit: to fix a typo from the transcript of his speech I was working from.