Adding formula to all existing formulas in an excel sheet

I'm setting up a monthly call tracker for sales and customer service. I have almost everything built out, but I'm looking to add the IFERROR function to all cells in the sheet that have a formula in them. Is there a blanket way to do this or do I have to do it one at a time. Below is an example of the different formulas I'm working with.

"=COUNTIFS('JAN DATA'!H:H,"Commercial",'JAN DATA'!I:I,"New Sales")""=SUM(SUMIFS('JAN DATA'!G:G,'JAN DATA'!H:H,"Commercial",'JAN DATA'!I:I,"New Sales"),SUMIFS('JAN DATA'!G:G,'JAN DATA'!H:H,"Commercial",'JAN DATA'!I:I,"Inspection"))/(E4+E5),"")"

I have 15 people I'm tracking and about 5 lines of unique code per person every month.

Thanks in advance