I believe at least one top player has been unable to adapt to his sponsor's equipment and has gone back to an older model.
I think "just adapt" is ignoring the fact that how much the aim changes is different on every kind of side spin shot. Unless you have some way of connecting the aiming compensation between all those shots, you have a lot of shots to relearn. And no, backhand english is not a complete solution.
I agree with you, there probably are many top flight players who have altered their equipment or tried something new only to dislike it. We all have some element of preference, but is the decision making specifically relating to deflection? or is it feel? or is it placebo/mental?
I know in many cases, that sponsored players (in many sports, and pool is no exception) will have custom, or specific elements tailored to suit, or even their own older personal equipment just 'stickered up' to suit whichever logo signs their cheques. I do think that different equipment does alter many things, but is it really too much for these top-flight players who are playing many hours a day to overcome?
Yes, but not if a lot of people are using the term some other way. There are lots of other examples in pool vocabulary including "throw" and "kick" which have radically different meanings in different communities. Even the word "english" is problematic as some take it to mean any kind of spin on the ball and others limit it to side spin.
Don't get me started on 'backhand English'

- not the wording, simply the actual action itself... I've had very long conversations about 'back/front hand English' with snooker pros/coaches, Chinese-8 pros/coaches and several American table players. Most of the coaches, or better players are not imparting this. They are lining up shots which impart spin prior to cueing down, and understanding the level of deflection from their cue.
As for wording, I am not fussed if you call it spin, action or English.
Kick is a funny one that took me a while to get used to... To me, that was always a bad contact between CB and OB. 'Squirt' makes me feel uneasy to say (a bit like how mother refrains from using the word 'moist'

). I'll keep calling it 'throw'
But that seems like a perfect way to describe what's happening!
Interesting your brain goes there, and I can see why. I can't think of a more suitable term than 'deflection' to describe what happens during ball to ball impact - carom or slide are the only other words I would use... and they apply in slightly differing contexts to me.
I've only ever understood the term 'deflection' to relate to how the cue and cueball interact. How the ball deviates from the line of intended travel.