It's good to have options and let the child/teen feel comfortable which that comfort is influenced by teacher(s), proper assessments. Here are 2 real life examples of people I know face to face....well:
1. 1 former close friend was put back 1 grade in elementary school (approx. gr. 4 or gr. 5) because probably her English language fluency was minimal when she immigrated to CAnada from Greece, with her family...at that time. She is my age.
Anyway, I think 2 yrs. later or something, she was put back in my grade level with other kids. And guess what: she graduated from accredited major Canadian university with 2 university degrees: 4 yr. BA in French Language and Literature. Then BA in Education. In Ontario, I believe you must have 2 university degrees to qualify to even teach in public elementary, middle and high school levels. She actually taught full-time at our former high school! Then....she became the French /Foreign Languages Dept. head in the high school. When you are dept. head in Ontario high schools, you also must teach. I believe the school also provided elective German and Spanish courses for students. Not after school. This is a high school of approx. 2,000 students.
2. A cousin's son, immigrated to CAnada when he was 9 yrs. old. The family lived with me for 2 months since I had some "tight" room while I was completing my graduate degree. The boy was put back 2 grades in elementary school becasue ...primarily of his English probably.
Anyway........ he completed high school and also graduated from a Polytechnical University (Ryerson University) in Toronto which is a large publicly funded university (just like Univerity of Toronto) in Computer Sciences. He is working IT in a Ontario government agency.
3. A brother-in-law who has a PhD and is an Engineering Professor (Engineering Sciences which can be the most theoretical/hardest engineering discipline) for past 30 yrs. at University of Toronto, did poorly in his final high school. In the 60's. Just shitty and not good enough to compete to get into any Canadian university engineering program...repeated his final year. He got in.
In both 2 cases, I can't even stress enough: sometimes a child knows they are good/smart but they are initially limited by language. This is why ESL is critical, plus at home tutoring...and the parents having an interest in encouraging their child. I was an ESL child, but born in Canada. I began kindergarten not knowing any English. My father was so adamant that we do well in school, including reading alot from library.
I had kind teachers. I also had some good friends...to socialize and use my English lanugage skills naturally. Like all children should.