The cache is not at the posted coordinates.
The numbers within the last column and those within the bottom row represent the sum of the 30 empty cells within the other rows and columns, respectively.
Simply determine the digit values within these empty cells to solve this puzzle.
The hidden letters below are provided to only illustrate the layout of the twins. N37 26.??? W121 53.???
| S |
W |
I |
T |
N |
14 |
| E |
T |
N |
I |
E |
21 |
| R |
E |
S |
N |
P |
16 |
| P |
N |
S |
E |
R |
16 |
| E |
I |
N |
T |
E |
21 |
| N |
T |
I |
W |
S |
14 |
| 30 |
12 |
18 |
12 |
30 |
|

Congratulations to first solver pfalstad and first finder Teo2865.