Only two kinds of people can attain self-knowledge: those who are not encumbered at all with learning, that is to say, whose minds are not over-crowded with thoughts borrowed from others; and those who, after studying all the scriptures and sciences, have come to realize that they know nothing.
Sayings of Sri Ramakrishna
意訳：自己認識の習得が出来るのは次の2種類の人々だけである。全く学問に縛られていない人々、詰まり、他人から借りた考え方で心が一杯になっていない人々と、全ての経典や諸科学を勉強した後、自分は何も知らない事に気付く人々である。
スリ・ラマクリシュナの言葉

一知半解　Icchi hange or Icchi hakai; Mandarin: yīzhībànjiě
ichi (icchi) = one, chi = knowing, han = half, e or kai = understanding
One of the connotative translation can be: The behavior of pretension that you understand something fully, although your understanding is shallow.
Wiktionary shows the explanation as; sort of understand; to only halfway understand; to be unsure of the meaning (of a word or phrase).
https://en.wiktionary.org/wiki/一知半解

Ignorance is Bliss, was said by Thomas Gray, 1716 – 1771, an English poet, letter-writer, classical scholar.
It can be ; 無知は至福　Muchi wa sifuku, in Japanese.
A possible interpretation: A stranger who knows nothing may be more fortunate.

Kindermund tut Wahrheit kund. Deutsches Sprichwort über die Wahrheit.
意訳：子供の口が真実のみを明らかにする。ドイツ語の真実に関する諺。
Eine konnotative Bedeutung kann sein: Die Worte des Kindes haben kein Hinten und kein Vorne.
一つの解釈：子供の言葉には裏も表もない。
Literal translation into English can be: Children’s mouths tell the truth. German proverb about truth.

Un cœur droit est le premier organe de la vérité. Proverbe français sur la vérité
意訳：真っ直ぐな心は、真理を体現する人間の第一の(内臓)器官である。 真理に関するフランス語の諺
Possible English translation can be: An upright heart is the first organ of the truth.

Yamada Yukihiko