Link Property to Source Text

TL;DR I need to know if & how I can make a property in a shape layer equal the numeric source text of a text layer. I want the number in that text box to then also become the trim paths "start" value.

I believe it is essential that the master source of the number be the source text of the text layer -- I am creating a bunch of videos from a single template using CompsFromSpreadsheet, which enables me to specify replacement text for different layers using that spreadsheet. These layers will contain percentages which I want to display as text and have reflected in a pie chart (which relies on trim paths).

So, ideally, I would be able to link the Start value directly to the number in the text box in some way.

Alternatively, I could have the value pull from a spreadsheet as well. I'm aware that there are ways to pull values from a .csv file in AE, however, in this case there will be hundreds of new comps generated at once (by compsFromSpreadsheet) and I don't know how I could have those comps each reference the correct cells in the spreadsheet to find the correct values. CompsFromSpreadsheet will be giving each of these new comps a name -- is there a way I could say "Start value for Shape Layer 1 equals Row[name of comp],Column 586", for example?

(Using AE version 23.4)