I was asked about this in a comment on an earlier blog so this should be considered a slightly overblown off the cuff answer - I haven't done any research or read deeply on the subject so all the opinions are mine and some of the facts may be wrong(1).
Roughly the question was - in the US version of the books why is Leslie called Leslie (as opposed to Lesley in the UK editions) and why does she suddenly revert. The answer is simple - cultural dominance and fear.
America is currently the culturally dominant nation in the world(2). This is particularly true vis a vis other English speaking nations where domination of the local culture is unmediated by a language barrier. Members of a dominant culture tend to be more resistant to having to familiarise themselves with other cultures including variant spellings and terminology. OK it's not everyone obviously or even a majority but it is enough to have an impact on sales.
So when an American publisher takes up a book by an unknown(3) author set in author's native town and written in the first person in the locality's colourful local vernacular they have a choice - leave the as is and risk alienating a financially significant percentage of the audience or make few harmless changes to smooth things along. It is, as they say, a no brainer.
Lesley vs Leslie
That explains sidewalk, soccer, bangs, chips and hoods - what about Leslie? I originally wrote Lesley's name as Leslie but my UK publisher said that the female version of the name was more usually spelt Lesley - so we changed it. Remember both publishers now have their own copies of the manuscript - they have diverged. My US publisher was quite happy with Leslie and so stuck with that.
However I now consistently spelt Lesley as Lesley in my manuscripts that now went to both publishers. In Moon Over Soho Del Rey, the US publisher, opted to change Lesley to Leslie to remain consistent. By Whispers Under Ground Del Rey, by now disappointed with the sales figures(4), probably couldn't be bothered - its hard to tell from this side of the pond. Anyway DAW took over for the next book Broken Homes and their policy is to just change variant spellings colour to color, herb to erb(5) um...look I can't spell in English English so I'm really not the one to ask about this. So Lesley stays Lesley from now on.
And now a Quick Word to them what don't like Peter saying 'Me and....'
The language or dialect spoken by the ordinary people of a country or region:
(Of speech or written works) using the mother tongue of a country or region: vernacular literature
(1) Pretty much internet standard then.
(2) Enjoy it while it lasts guys.
(3) Yeah, yeah, Doctor Who yada yada - effectively unknown in the US.
(4) I currently sell 10 times as many copies in Germany (in German) than I do in the US. Hah! So much for the homogenous Science Fiction anglosphere.
(5) Yes I know - this is me being funny (or possibly not).