Regards to 4:171,
The phrase "in a Trinity" translation is not in the Arabic text, neither was it put in parentheses to indicate the interpolation. Carefully note that the Qur'an has preserved the divine splendor of Jesus by referring to him as "His (God's) Word" and "Spirit proceeding from Him (God)."
The phrase "Spirit proceeding from Him", the Arabic for this is "ruh-un min hu" and is found elsewhere in the Qur'an. (read 58:22)
Yusuf Ali translation, there is a footnote No. 5365 which describes this "Spirit from Himself" as "the divine Spirit which we can no more define adequately than we can define in human language the nature and attributes of God."
Obviously this same phrase "Spirit from Him (God)" which the Qur'an uses to describe Jesus in 4:171 is speaking of one who is more than just an ordinary prophet!
No confirmation of textually corruption here.
”(that is now unnecessary)” (5:15)
Was Yusuf Ali inspired to add this text when all the others (Pickthall, Shakir) did not?
”blasphemy" (5:18 & of course verse 17)
How can Yusuf Ali translate “disbelieve” (read Pickthall, Shakir, and Sher Ali translations) to “blasphemy”? Not believing a certain claim is not the same as blaspheming.
Here again, no mention of textualy corruption of the Bible.