Paper crafts of blue and brown express coaches are these fan made papercraft files that have been online since the early 2000s, making them predate the official ones released with the talking Plarail engines. Probably just a coincidence because both originally come from Railway Series illustrations.
http://plathomas.gozaru.jp/
Backdated ST-nn numbers refer to boxes where the ST-nn number was seemingly misprinted and corrected with a sticker after the fact. I have run into several places where it seems Tomy used earlier printed boxes for a few years after (such as the mentioned 1995 Gordon boxes which appear as late as 1997) but I have only seen this "backdating" once myself, on this 1997 Percy where the box originally said 1999 but a sticker was put over it. ST-7 matches the Percy in the box and the box style itself (a real printed 1999 box would have the Tomy website URL in the bottom right, as seen below)
James Made in Japan/v1 box is the original release of James, which should have a slightly different box that I have not yet seen a photo of. It will at least differ from a v2 James box in that it will say "Made in Japan" instead of "Made in Thailand." There may be other differences but I have never seen one to know.
Currently, I suspect there is not a UK logo James box and it was always the Britt logo from the start, but until I see it confirmed one way or the other my spreadsheet of box revisions contains the possibilities of both a single MiJ Britt logo box and a MiJ and short-run Thailand UK logo style box (both Thomas and Henry follow this pattern).
The Plarail magnetic couplings are an old Plarail addon where you could replace the couplings with magnetic ones. The "loop" coupling replacement is very similar (but moulded ever so slightly differently from) a Tomy Trains coupling, but the "hook" replacements have an added joint via a screw.
Very recently (I just won the auction earlier today in fact) I became aware that someone in the UK got their hands on them at some point, and from the way it is worded, it seems like possibly they were purchased back in the day when their kids were playing with the toys new.
Most likely they were just imported in some way, but saying "one guy imported some Plarail magnetic couplings to the UK" is a lot less boring on an iceberg then speculation they were available for regular sale in the UK
Talk n Action Percy and James REDACTED has been withheld. It's a bit of a "joke" entry but does have an interesting story behind it, more of an inside joke a few people know (originally I made this iceberg for the amusement of a Twitter group chat).