This line is wrong:

<<Therefore, all in all, I had $18,076 in charitable deductions.>>

(Maybe 18076 in itemized?)

The refund worksheet will calculate that only X% of the income taxes paid were really deducted (10000 / 10453 = 95.6%) and since 8536 /10453 was the income tax piece of the total, x 95.6% was deducted,  depending on the Std Deduction for your TP, only 81.67% X 95.6% of the $691 refund is taxable income.

I think?