Modifications:

I worked 2.5 inches (3 cable crosses) before beginning the thumb gusset

I worked the gusset decreases every 3rd round instead of every other round

I completed a total of 8 cable crosses from the cast-on edge, worked 5 more rows, then cast off using the long-tail bind off, which is a type of sewn bind off that mimics the look of the long tail cast on.

The pattern instructions define as C4F as holding the cable needle to the back and C4B as holding the cable needle to the front, which is the opposite of any C4F/C4B I have ever seen. Judging from the picture of the mitts, this is a typo, and “back” should be “front’ and vice versa.