We're seeing this An unhandled exception of type 'System.ArgumentOutOfRangeException' occurred in mscorlib.dll Additional information: Rounding digits must be between 0 and 15, inclusive. coming from ExcelGeneralNumberFormat line 98.

This is caused by a wrong data type used in the digits counting algorithm. When calculating the len on line 96:
int len = (int)Math.Log10((**int**)Math.Abs(value)) + 1;
Casting a double to an int, you can easily end up with int overflow. When this happens, you end up with len like -2147483647.

Numbers higher than 10,000,000,000 are handled correctly line 77. But there is plenty of numbers between max int 2,147,483,647 and 10,000,000,000 that trigger the overflow.