I want to know the answer to the following question:
What do professional and amateur singers often sing?
All the background I'm provided with is that "Translations of sung texts—whether of the above type meant to be sung or of a more or less literal type meant to be read—are also used as aids to audiences, singers and conductors, when a work is being sung in a language not known to them.". Is that enough to answer the question?
Answer: no