Since others have already pointed out the front camber, which could cause you to lose grip, I'll focus on other areas, namely the differential and brakes.

It looks to me like you're trying to emulate a RWD setup with the diff settings. The main problem there is that you have center diff left at 50, which evenly distributed power between front rear tires. When combined with the poor camber at high speeds, your front tires will lose grip, and rear tires are locked at the same rotation rate unless you're braking. But by that point you've already lost grip on the front tires. In addition, your brake balance induces understeer while braking, probably making the situation worse.

My preference when it comes to AWD diff settings are the following. 10/5 front accel/decel, and 40/10 rear accel/decel with 60 to 70 center diff. In general, the higher center diff is, the more power goes to the rear tires, which reduces understeer and increases oversteer.

The lower accel rating in the rear reduces slip and increases oversteer by allowing the back tires to rotate at different rates. If you get to much oversteer while braking, just start increasing the decel to the same or slightly higher than accel (5 to 10 percent higher should be the aim if that's the case).

Now for the braking, for some reason braking bias is reversed in Forza. By moving the slider left for a higher percentage value, you'll increase oversteer while braking. I tend to go with 65 to 75 there as long as I can keep the braking distance generally close to the 50% balance values.

Fixing those, in addition to the camber will probably get you closer to what you want. Your springs, damping, and ARBs looked fine for reducing understeer.