Dear Stef,
I agree with your observation. I'd have to trace through all of those formulas to see what is going on.
Those spreadsheets are old. If you are interested in SAM's Residential, Commercial, or Single Owner financial models, I would recommend generating an Excel workbook from the Cash Flow tab on the results page (click Send to Excel with Equations. That will generate a workbook with input variables populated from SAM with formulas that you can trace.
Unfortunately that feature is only available for Windows versions of SAM.
Best regards,
Paul.