You have the watchman part correct, which it is us proclaiming the word, and using the commandments to bring to the light those how are in darkness in hope they will see the wrong of their ways and turn to the Word and see His light.
The righteousness of the righteous man shall not deliver him in the day of his transgression; as for the wickedness of the wicked, he shall not fall because of it in the day that he turns from his wickedness - The above is very clear how God sees each one of us as well as any nation, so this is not just addressed to the children of Israel.
nor shall the righteous be able to live because of his righteousness in the day that he sins - Again, God give clarity that, if we fall away from His ways and statutes, our righteousness will be as dirty rags. -
he trusts in his own righteousness and commits iniquity, none of his righteous works shall be remembered; but because of the iniquity that he has committed, he shall die.
God continuous,
Again, when I say to the wicked, ‘You shall surely die,’ if he turns from his sin and does what is lawful and right, 15 if the wicked restores the pledge, gives back what he has stolen, and walks in the statutes of life without committing iniquity, he shall surely live; he shall not die. 16 None of his sins which he has committed shall be remembered against him; he has done what is lawful and right; he shall surely live. God shows how His mercy works with the people of Nineveh in the time of Jonah.
I know that some people believe in 'once saved always saved cause God cannot go back on His word', the above clearly shows that it is not God going back on His word, but us returning to our wicked ways; hence removing our names from the book of life.
This is my personal understanding of the matter above, and I have asked in prayer for clarity if otherwise many times.
Amen