英语口语到达彼岸怎么说

"Reach the other side" is a common way to say that someone has achieved fluency in English speaking. You could also say that someone has "crossed the threshold" or "arrived at the other side" in reference to reaching fluency in English speaking. Here are a few example sentences:
She worked hard to reach the other side of English fluency, and now she speaks the language with confidence.
He spent years practicing and studying, and now he has finally crossed the threshold of English fluency.
After years of dedication and hard work, she has finally arrived at the other side of English fluency.
I hope these examples help! Let me know if you have any other questions.