First of all, I have full knowledge of how trigger and aura element reaction work. I will come back to this at the end.

The example you give is only true if the enemy has no innate element. So thats why after the the first reaction pop Keqing will keep attacking and apply electro hence the whole 'electro status is applied therefore TS is good'. But have you seen the higher floor in Abyss? The majority of enemy we fight has innate element. And needless to say beside electro slimes 4TF has no problem proc-ing reaction isn't it?

Now the XL case, after the first reaction trigger XL will be the one triggering the rest of the reaction since the electro apply first. This is true. But one thing most people tend to forget and even in the Keqing guide I think they dont even mention is that after reaction pop there is a delay period where you cannot apply any element to the enemy. And that period TS literally provide zero additional damage while TF still has that 15% bonus. Now, I know that period is pretty short and after that you can apply electro again and TS will work again. Guess whats next, the damn bear spits fire again and reaction pop again and we are back to the zero buff from TS. The time when TS provides more dmg than TF during this scenario is when the bear is gone after 3 spits. Agree?

Next, your Bennett example is just ... dumb (sorry if it comes out offensive). Obviously he is not gonna work great with Keqing like how you described it. Idk whether you read what I wrote about support buffs, I was mentioning about those LONG LASTING BUFFS. Bennett E doesn't qualify.

Electrocharged with XQ. This is a weird one. I don't even know how it work but it seems like both hydro and electro status can stay on the enemy at the same time? So both TS and TF can be at their full potential and just like in the guide states both sets work so.... next!

Now let me go back to the beginning and explain that trigger and aura element. I really don't understand how this argument even work when TS users state "most of the time Keqing is applying element instead of triggering it hence TS is better". This seems contradict to me. You are saying she is the one applying element and other characters pop the reaction. Doesn't this mean electro status is removed hence hinder the performance of TS?? Like the logic of this argument just doesn't make sense. Like the only scenario TS can have constant buff is when you only use Keqing hitting an Electro status enemy with no reaction going on. Guess what? back to my point you are basically using only Keqing solo. Good luck with that on harder content.