I'm trying to make a tracker that logs values by position, and I need to find a way to make each new position display a list of the previous positions that had an equal value (the "problem section" in the screenshot). I'm fairly new to Excel and haven't ventured into VBA yet, so I'm hoping to find a way to accomplish this with formulas but without an entire worksheet's worth of helper columns to make it happen. I'm willing to attempt VBA if necessary for such a task, though. To make things even more fun, it needs to be built on Excel 2016, so I can't use some of the more modern formulas.

My instinct is to use a sequential formula which adds the last position to its own PREVIOUS tab (ie, =F9&", "&D9 for F11), but the only way I've done similar things in the past are with continuous data, which this is not, so I can't just do one chain, and I can't use INDEX/MATCH without it going to the top rather than the previous. Any advice would be greatly appreciated.