Almost any property that can be animated will generate usable values you can use in another expression. There are exceptions, like Curves, but if you can generate a numeric value you can use that to generate a value in another expression.
If you have a range selector animating the Y position of a line of type you could compare the range selector value with the position and calculate how much the Y position changes as the characters move.
To be specific we need a detailed description or sketch of your design goal. Something like "I have added a Position animator to a text layer that makes text fall from the top of the frame to their final position. I want to automate the Source Point of the Shine effect so that it jumps to the top left corner of each character as it hits its final position and then I want the Boost Light to flash then fade as the next character falls into position."
If that is what you wanted to do then I would start by opening up the Advanced options of the Range Selector and changing the units to index, then I would retrieve that number and round it so that as the range selector moves from 0 to 1 nothing would happen until it got to 1. That would trigger a time-based increase in the Boost light, and a position jump equal to the distance between the characters. The expression would require accumulators and if/else statements, and I couldn't write it without AE open and a lot of fiddling, but somebody like Dan Ebberts could probably knock it out in a couple of minutes. We just need to know what you want to accomplish.
(edit) So I opened up AE and added Shine to a text layer then added this expression to Source Point. Set the Source point to the center of the first character using a monospaced font and set the number of characters in the expression and the source point jumps to the center of each letter as it starts to move. Maybe this will get you started.
v = text.animator("Animator 1").selector("Range Selector 1").end;
charCount = Math.floor(v);
txtWidth = thisLayer.sourceRectAtTime().width;
charWidth = txtWidth / 10; // Number of characters in text
newX = charWidth * charCount;
[value[0] + newX, value[1]]
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