Here is something I've struggled with. I am Australian and yet the Walker Saga is set in an American setting. I haven't been brought up living without television or books so I have obviously been exposed to American culture. BUT I am Australian, the sayings, wordings I use probably reflect this. And I'm an Indie author, I assume in the big pub companies, they have people who help tone down the language differences. :)
I actually never realised how many slang/sayings Australian's use that are unheard of in other countries; we have many. Living in Canada for a year definitely taught me the vast differences between our cultures. I'd say, "she's feelings a little off-colour," and blank faces would reflect back. Okay, you don't say that when someone is sick? Weird.
In Canada they thought my Australianisms were cute, in my writing, not so much.
And the UK; I think they have a very unique slang and way of speaking, although there are a few more comparisons between our countries. I wish I had lived in each and every country so I could fully immerse in their language and culture. Now that would be a useful skill.
So, I guess I live with the fact that not everyone is going to enjoy my style of writing, or even get my humour and sentence placements. And that's totally okay, we are all different and like different things. I can only hope I continue to learn, grow and expand my knowledge of a writing style that is more universal. But at the end of the day as long as some people like it I'm excited.