The fundamental problem is this. There a wide variety of issues that progressives embrace such as Medicare 4 all and wanting to see that Military budget slashed in the USA.
The DNC tries to claim they will address all of these issues under the banner of the Democratic party which is absolutely false. They have not done anything like that for 50+ years. This progressive caucus accomplished nothing yet claim that if they persist their time is coming , again a demonstrably false statement.
I do not think the DNC down in the USA can be reformed from within. It sold out long ago and they know they can take far too many of the progressive votes for granted (They JOKE about it saying they have no where else to go)
I do not think there any distinction to be made between the progressives and the liberals just as long as those progressives remain inside the DNC and evidence of this is there for all to see with votes such as this.
If the true progressives and left want to be seen as distinct from the “liberals” in the DNC they have to leave the party and form a third party. They will get far more done.