Well, from what my parents told me (my mother took her motorbike test about 10 years ago), they simply worked around it. Instead of giving commands as they go, the instructor told my mother what she would do and when she should do it and then they went ahead and did it. In most tests (here in Britain at least) you stop every ten minutes anyway to do a manouvre or to discuss what will happen next - in these discussions an interpreter can be sat in the back seat and give assistance when needed.
It may take a little extra effort but it’s easily worked around. My mum passed first time 
Fran