Here's a solution for you that should get you going now:

1. Go to c:\Program Files\VEGAS\Vegas Pro <version>\Script Menu

2. Open "Batch Render.cs" in a text editor such as NotePad

3. Look for this section (about 52 lines down):

        DialogResult result = ShowBatchRenderDialog();
        myVegas.UpdateUI();
        if (DialogResult.OK == result)
        {
            // inform the user of some special failure cases
            String outputFilePath = FileNameBox.Text;
            RenderMode renderMode = RenderMode.Project;
            if (RenderRegionsButton.Checked)
            {
                renderMode = RenderMode.Regions;
            }
            else if (RenderSelectionButton.Checked)
            {
                renderMode = RenderMode.Selection;
            }
            DoBatchRender(SelectedTemplates, outputFilePath, renderMode);
        }

4. Now let's modify it so it will do it individually for every track by changing the above to:

        foreach (Track myTrack in myVegas.Project.Tracks)
        {
            myTrack.Mute = true;
        }

        foreach (Track myTrack in myVegas.Project.Tracks)
        {
            myTrack.Mute = false;
            CurrentTrack = myTrack.DisplayIndex;
//The bold section here stays the same with no changes. We are just adding code around the bold section!
            DialogResult result = ShowBatchRenderDialog();
            myVegas.UpdateUI();
            if (DialogResult.OK == result)
            {
                // inform the user of some special failure cases
                String outputFilePath = FileNameBox.Text;
                RenderMode renderMode = RenderMode.Project;
                if (RenderRegionsButton.Checked)
                {
                    renderMode = RenderMode.Regions;
                }
                else if (RenderSelectionButton.Checked)
                {
                    renderMode = RenderMode.Selection;
                }
                DoBatchRender(SelectedTemplates, outputFilePath, renderMode);
            }

            myTrack.Mute = true;
        }

        foreach (Track myTrack in myVegas.Project.Tracks)
        {
            myTrack.Mute = false;
        }

What this does is first mute every track. Then it goes through the tracks, unmuteing one track, render the regions on that one track, and then mutes it again. Once all tracks have been individually rendered, it then unmutes all tracks. Unfortunately, every track rendered would overwrite the previous track's render without a couple more changes. So let's add the current track as a variable at the top of the script - change:

    ScriptPortal.Vegas.Vegas myVegas = null;

to:

    ScriptPortal.Vegas.Vegas myVegas = null;
    int CurrentTrack = 0;

And then change where it sets the file name from:

            if (RenderMode.Regions == renderMode) {
                int regionIndex = 0;
                foreach (ScriptPortal.Vegas.Region region in myVegas.Project.Regions) {
                    String regionFilename = String.Format("{0}[{1}]{2}",
                                                          filename,
                                                          regionIndex.ToString(),
                                                          renderItem.Extension);

to:

            if (RenderMode.Regions == renderMode) {
                int regionIndex = 0;
                foreach (ScriptPortal.Vegas.Region region in myVegas.Project.Regions) {
                    String regionFilename = String.Format("{0}[{1}][{2}]{3}",
                                                          filename,
                                                          CurrentTrack.ToString(),
                                                          regionIndex.ToString(),
                                                          renderItem.Extension);

Naturally the file naming could be modified however you desire to get the naming designation that you want. So you might just change the "String regionFilename" section to something like this to better match your naming description from your original post:

String regionFilename = Path.Combine(outputDirectory,
                                           FixFileName(region.Label) +
                                           "_" +
                                           "Track" + CurrentTrack.ToString() +
                                           renderItem.Extension);

5. Save this as a new file name such as "Batch Render Tracks Separately.cs" or whatever name you prefer.