There are 2 ways you can translate lessons to other languages in the course.
Please go to Dashboard => LearnPress => Quizzes=> Click to Add translation.
Please go to Dashboard => LearnPress => Quizzes => Edit a quiz => Click to Add translation.
After clicking Add translation, you will need to type name, description and configure like when you create a new quiz.
NOTE: After translating, you need to assign quizzes to a course.