Out of curiosity I checked the updated JT assets. The SWEX RouteProperties.xml points towards Assets\JT_AddonPJ\TemplateRoutes\a25_bristol_exeter.xml. This file is responsible for settings up the seasonal skydomes, and for default texturing when using it for Route Creation. Two things I noticed, the first is that besides the packed .bin file there is a file a25_bristol_exeterxml (missing period) - suspicious, but nothing to worry about as this file is not used if the corresponding .bin is present. So I tried to unSerz the a25_bristol_exeter.bin - which I had to Ctrl-C (stop the process) becausing the output file would grow rapidly to no limit. Which means that this file is corrupt. I took a look at both RouteProperties.xml and the a25_bristol_exeterxml to create a fixed templateroute file. RouteProperties.xml - the marked TimeOfDay files do not exist a25_bristol_exeterxml - all of the season files do not exist! next, the texturing file referenced points to an 8-byte file (SERZ header only) Very weird. Did JT rush this thing? I have compiled a new templateRoute file, using the predefined JT_AddonPJ\TimeOfDay files, and the texturing file used points to JustTrains\SWEX\Environment\Terrain\Texturing.bin now. I have also changed the DisplayName to not conflict with the original Bristol-Exeter template file. It's now listed as JT SWEX Reading in the route editor templates. In the .zip you'll also find an updated correct RouteProperties.xml (plus backup file) I will file a bug report to Support too. Enjoy.
Thank you for flagging - will respond to your Support ticket too, but I've sent it through to our Third-Party team to follow up with JT.