This change make it almost certain that books where the publisher is listed as Ladybird (or in one case Puffin) are for the United Kingdom - running in parallel with the American tie-ins from Grosset & Dunlap. All three publishers are children's imprints of Penguin Books.
The most noticeable change is the addition of "unapproved" cover art, presubably preliminary designs; but it's notable that the release dates for these books have been moved up to 7th August from 1st September, and that two of them have had their language listing changed from French, a detail which was causing us some confusion earlier.
It thus looks as though the situation is simple: US children's tie-ins from Grosset & Dunlap on 26th July, UK ones from Ladybird on 7th August. I expect the remaining listings claiming that books will be in a foreign language and/or released on 1st September will be updated in due course.
How much variation there is between the two ranges in the UK and US, however, remains to be seen.
Thanks once again to the ever-reliable Eddie from fan-site Once Upon A Galaxy for pointing some of that information out, and inspiring me to hunt down the rest!
UPDATE: as we reported here last night, the "unapproved" cover art on the Amazon UK website has disappeared. Thanks to Zee Zee from UK-based fansite Star Wars Books for spotting that.