Those in the crowd were uncertain about His cry. Certainly the weakness of the voice due to the physical suffering contributed to the uncertainty.
Normally when referring to the Scriptures Jesus preferred the Septuagint translation. But here He cried in the language of the land.
Both the cry and the language speak to His humanity. In this agony He returns to the language of the people which interestingly, isn't clearly understood.
How can this be understood? The promised Messiah is prophesied to be God Himself Isaiah 9:6. He is both Everlasting Father and Mighty God. In Isaiah He is God with us. And in Zechariah 14 it is the LORD that shall go forth. This Messiah is the God of Creation, and this Creator has come to the land as fully man. And lives His life in this land, and in the language of this land He cries His final words.
He Who made and spanned the splendor of the Cosmos limited Himself to a language and to a land. And because of Him, one day I will fly away from this land.