LearnDash plugin helps you to style your website in a way you want to style it. So it’s basically a plugin not a Theme.
LearnDash is very easy and flexible. Also is saves your time of development. Thus, overall it saves your time, money and give you effective result.
LearnDash doesn’t demand for a particular theme structure to be compatible with. So that generic themes are compatible with LearnDash.
Yes, any of the wordpress theme can be translated. Thus, LearnDash wordpress plugin can also be translated.