YOU SAID:

If it was not for their unending lack of understanding

INTO JAPANESE

それは終わりのない理解の欠如のためではなかった場合

BACK INTO ENGLISH

If it was not for lack of understanding at the end

INTO JAPANESE

最後に理解の不足のためではなかった場合

BACK INTO ENGLISH

If it was not for lack of understanding at the end