1) Ihatov is a fictive place where Miyazawa Kenji’s (a Japanese author) stories and poems are set. It’s a very mysterious one. If you want to read up more info about it, take a look at this article!
2) The “untranslated” parts are written in the language of youkai, thus “we humans cannot understand it” (comment by Stack).
3) Mayohiga is a place full of cats. Its name would translate to “Stray House”. As I commented on “Destiny ~ Spring has come at last”: Blame Chen!