Most of these "chapters" are multiple galleries from pixiv stitched together by me and broken up by the author's end cards, this one was three galleries. I've made the chapters based on the end cards, which the author was consistent about. I've left the title cards in but their numbers don't make much sense, I would recommend ignoring them.
Start of this gallery has a page stating chapter 3, midway through, suddenly we're in chapter 2?... and then at the very end, it matches the gallery title saying end of chapter 5
The order is still incorrect, the chinese versions that are also available in EH are more coherent.
1st gallery should come after chapter 3 that you posted and before chapter 4. 3rd gallery is correct as the start of this chapter. 2nd gallery is also correct as it happens after the content of the 3rd gallery.
So the biggest problem is the 3rd gallery being completely out of place since it happens before chapter 4.