I believe the galleries from 1 - 9 can't be viewed from chapter 10 and beyond because chapter 10 and beyond IS a separate game. The saves (all your choices and shit) are just exported and grabbed by Ch10+ but NOT the scenes/videos/whatever. So if you could view 1 - 9 from Ch10+ you'd just get the standard Ren'Py error saying the image is missing.
I believe this is done as a way to reduce file size. As Season 1 (chapters 1 - 9) combined with Season 2 (chapters 10 to probably 19 or something) would probably make the game about 15 to 17GB. So by splitting it in half Season 1 is only 8.2 GB and Season 2 would be around the same size. Then you just download and complete Season 1, delete it, then download and complete season 2, delete it, then repeat for Season 3 if there is one.