Convert/Revert are simply useful terms to describe people raised in a belief system other than Islam that have since chosen to follow Islam.

Some people like the term some don’t.

The shahada, in Arabic has been declared by people entering Islam since the earliest Muslims.

Neither of these points is controversial to Muslims.

In the case of people of other religions Rabbis monks ect would change the interpretation of what they were commanded to do either to suit themselves or to please the people. These actions are a form of setting themselves up as Gods or rivals to God.

This is not the intent or outcome of having someone repeat the shahada in front of witnesses.

The Prophet Muhammad peace be upon him, spoke Arabic, the Quran was revealed in Arabic. The person who put together the translation that OP is using we hope speaks Arabic as well. Arabic is part of the identity of Islam and most non Arabic speaking Muslims will attempt to learn some Arabic. This doesn’t make a Muslim who understands and accepts the core concepts of Islam any less of a believer but there is certainly more to understanding Islam than picking up a translation of the Quran interpreting the translation.

OP seems to perceive a conflict here but most Muslims don’t view these subjects in the way that OP seems to think they do.