Put them back two or three grades. That is what used to happen with the non English speaking immigrant children of the past.
I had a really old Lebanese friend - she passed away at 100 several years ago - who was put back two grades and did not suffer for it. Later became a school teacher.
An older friend from Norway was put back a year and later became a very successful and wealthy salesman and business owner.
The more the kids are coddled, the less able they will be to achieve.
Put them back a couple of years? No problem...that’s standard practice in Southlake. Our middle school teams compete against the equivalent of freshman and sophomore players. Not that big a deal in basketball, but we’re outmatched in football.
When I was in sixth grade we got a girl in our class that was several years older ans did not speak English. The teacher had me help her as I always made good grades. I ended up helping her for three years, we became good friends, she learned English and I learned Spanish.