Beware you'll be spoiled if you watch the video series before playing Hollow Knight (she played it until the ending).
{kouki na} monoyo, korewa {sonatadakeni tsutaeru} kotoba. 高貴な者よ、これはそなただけに伝える言葉。 {Noble} one, these are words {to convey to you alone}. Higher beings, these words are for you alone. (original English)
kore yori saki, sonata wa ou to souzoushu no chi ni hairu. これより先、そなたは王と創造主の地に入る。 Beyond this point, you'll enter the land of the king and creator. Beyond this point you enter the land of King and Creator. (original English)
sono shikii wo koe, ware-ra no hou ni shitagau ga ii その敷居を越え、我らの法に従うがいい。 Cross its threshold and obey our laws. Step across this threshold and obey our laws. (original English.)
soshite mokugekisha to naru no da. そして目撃者となるのだ。 And become witness.
{{saigo ni} shite} tada hitotsu no bunmei, {eien naru} oukoku, "Harounesuto" no. 最後にして唯ひとつの文明、永遠なる王国、”ハロウネスト”の。 The culture [that] {is {the last} and} the only one, the kingdom [that] {is eternal}. Of Hallownest. The {{last} and} only culture, the eternal kingdom. Of Hallownest. Bear witness to the last and only civilisation, the eternal Kingdom. Hallownest. (original English.)
The Japanese version ends with a no-adjective that qualifies mokugekisha of a previous sentence.
Harounesuto no mokugekisha to naru no da. ハロウネストの目撃者となるのだ Become witness of Hallownest. Become Hallownest's witness.