This initially confused me. I assumed the dictionary of obscure sorrows was a list of existing words for obscure sorrows, but I know watashi ato means “I” “after” literally in Japanese so it didn’t sound like a real word. The words in the blog are actually invented to describe obscure sorrows.
watashi can be 渡し rather than 私, which means "to pass"
I can't find a dictionary definition for 渡し跡, but you can find a few blog articles talking about old places that use this word. I think it might be an older Japanese word.
https://shinsengumi-kanko.com/nagareyama-noda/yakkarawatashi...
