Building a dynamic formula

I'm using Excel to predict the capacity usage of storage devices. It's clunky, but it works great until someone changes the name of the SharePoint folder I'm using to reference my data. (This has happened twice) I had the brilliant idea (or so I thought) to dynamically build the formula using "concat", which I thought would allow me to simply change one cell and be able to affect all of my entries (about 65 rows).

I then learned that "concat" only builds the formula, it does not evaluate it and that I needed to use "indirect" to evaluate it. That worked, except my output was "REF", not what I was expecting. After a little more digging, I found that "indirect" does not work with external workbooks that are not open on the local machine. (I don't want to open 60 workbooks to get the data I need)

It looks like I am out of luck, but I am hoping someone else has a brilliant idea I have not considered yet.

Thanks