My friend and I kind of disagree on the nature of 2 errors in a sentence.
The sentence + the context:
My friend read an advert from an English teacher who wrote (I'm only quoting the relevant sentence): 'I'm most experienced teaching conversation, but it's of course up to you what we learn.'
Now, he's adamant that this sentence is incorrect and that it contains 2 basic errors and that it should have been:
I'm most experienced IN teaching conversation, but it's of course up to you what we'LL learn.
In essence, I agree with him in the sense that I also would have said 'experienced in' and 'it's up to you what we'll learn'. However, I'm of the opinion that I wouldn't really be shocked if I heard it from someone. It does sound a bit clumsy but I don't consider those 2 errors to be unforgivable. To me, they seem as something a person could write when not paying attention or not taking enough time to properly put their sentence together. He keeps arguing that this is something a native would never write while I keep saying that it's not super natural but I wouldn't be surprised to hear 'I have experience teaching' and 'it's up to you what we learn'. Basically I think this error is not as tragic and unforgivable as he makes it out to be.
Do you consider this to be standard usage or would you consider it an error?