I would hope a mechanical engineering degree and relevant career path plus real racing experience (and that doesn't just mean driving) have meant Tristan is slightly more likely to understand this than you, in fact I think my cat could comprehend enough of this if I drummed it in enough so another go:
1. You're driving with keyboard controls, ditch them straight away. If you insist on using this silly input method you'll have to adapt the car to cope. Those who drive fast do not use such a silly input method therefore by that logic WR sets will be useless for you.
2. The softer compounds now heat up more quickly, I'm certain you're overheating them, you need to change the tires to suit your driving style and race distance. A hot lap set will now be even more useless because it'll use the softest available tire (R2) that can no longer last a pick up race.
3. The camber needs to be changed in setups from the last patch. You're complaining of understeer, presumably through the front tires over heating, maybe through too much camber. A quick glance at Art555's table shows a lot more negative camber has been added to the front of the BF1, which only draws me to the conclusion that the set you're using is old and useless to you.
4. I've raced against you once or twice and you're not a good clean driver. Honestly you're all over the place and you've only got vaguely competitive by driving 5000 laps round one combo that very few people practice very much. I seem to remember you complained about the changes to Blackwood as well, you're clearly just a creature of habit and are upset you've lost the one combo you've somehow become competitive at. I suggest you find a better controller and try a slightly more interesting and challenging combination of a completely different car and track.