Need help with Expression problem

The first thing you need to do is line up the anchor points. For left Justified text I use the following expression to put the anchor point at the bottom left corner of any text layer.

txtBox = sourceRectAtTime();
h = txtBox.top + txtBox.height;
w = txtBox.left;
[w, h]

A few more expressions will let you line up the text layers and add a shape layer for the background. Put the shape layer below the text layers and add three sliders named Line Padding, Height Padding, and Width Padding. 

Now stack the text layers using this expression on the bottom text layer's position property:

ref = thisComp.layer(index - 1).position;
txtBox = sourceRectAtTime();

txtH= txtBox.height;
hPad = thisComp.layer("Background").effect("Line Padding ")("Slider");
[ref[0], ref[1] + txtH + hPad];

With the anchor point expressions and the position expression on the bottom text layers you'll get a perfectly lined up couple of text layer separated by the Line Padding value.

Now it is time to work on the Shape layer Rectangle and set the Rectangle size. This is the expression for Contents/Rectangle 1/Rectangle 1/Size:

ref1 = thisComp.layer(index - 2).sourceRectAtTime();
ref2 = thisComp.layer(index - 1).sourceRectAtTime();
h = ref1.height + ref2.height;
w = Math.max(ref1.width, ref2.width);
linePad = effect("Line Padding ")("Slider");
hPad = effect("Height Padding")("Slider");
wPad = effect("Width Padding")("Slider");
[w + wPad, h + hPad + linePad];

Then add this expression to the Shape Layer Anchor Point:

p = content("Rectangle 1").content("Rectangle Path 1").size/2;
hPad = effect("Height Padding")("Slider")/2;
wPad = effect("Width Padding")("Slider")/2;
[-p[0] + wPad, p[1] - hPad];

And finish that off with this expression on the Shape Layer Position:

btmRef = thisComp.layer(index - 1).position;

This should give you something like this:

And a comp that lets you move the top text layer anywhere and make the lines as long as you want. Something like this:

I hope you followed the logic of the workflow. 

You generated expressions give you the ability to wipe on the text layers, but make no adjustments for multiple layers or line up the anchor points. 

I modified your project a little bit, but I don't have the time to clean up the wipe by modifying the code generated by Animation Composer. It's a handy tool, but it creates code that's very difficult to read and modify.  I would probably rewrite the code for the Range Selector/Start. I hope this gets you started.