You could try a little acetone, but be careful it will likely cloud the area around there too. Also some clear touchup paint or nail polish may help. My thought is that the discoloration comes from the plastic bending/heating when it was being snipped. You'd have to get through the discolored part ...

Could either of you guys post some close ups of how you did it?

I’m very unclear on the placement of the fan.

Does the airflow come out the side of the fan?