GPT-5.3-Codex vs GPT-5.5for spreadsheets & Excel

You have **one definite formula fault** and one likely logic issue:

1. **`VLOOKUP` column index is invalid**  
   - `Sheet2!A:D` has only **4 columns**, but you asked for column **5**.  
   - This must be `4` (or expand the lookup range).

2. *(Logic, not syntax)* Your `SUMIF` criteria `">"&TODAY()-30` includes **everything after 30 days ago**, including future dates.  
   - If you truly mean “last 30 days”, use `SUMIFS` with an upper bound too.

### Minimal corrected version (fixes the hard error):
```excel
=SUMIF(A:A,">"&TODAY()-30,B:B)+VLOO…

Faults:

1. **`VLOOKUP` column index is invalid**  
   `Sheet2!A:D` has only **4 columns**, so `VLOOKUP(...,5,...)` is impossible. The largest valid column index is `4`.

2. **The date criterion should be parenthesized for clarity**  
   Use `">" & (TODAY()-30)`.

Corrected formula:

```excel
=SUMIF(A:A,">"&(TODAY()-30),B:B)+VLOOKUP(C1,Sheet2!A:D,4,FALSE)
```

If you truly need the 5th column, then the lookup range would have to include column E, e.g. `Sheet2!A:E`, but you said Sheet2 only has columns A to D, so `4` is the correct maximum colum…