Formulas or VBA better for this application?

It seems to me that you have made this far too complicated. All the data could be on one worksheet and with the use of Auto Filter, extract all the reports that you have on each individual's worksheet. If you convert the data on 1_ImportedData into a table with a Total row, you can get various counts as you filter the records.

The use of a Pivot table that uses the data on 1_ImportedData will summarize all your data very easily.

It appears that the Green, Yellow and Red are just counts of the various inventory items which are already incorporated into the 1_ImportedData worksheet.