You can import anything if you keep it private. It would only infringe the copyright if you share content that is meant for private use only, like the ebooks you’ve bought.
People are using LingQ like this regularly and it isn’t an issue, so no worries.
In regards to the language aspects choosen, I think these terms are used to filter out suitable content for you to display. I think you can change those later on, but in all honesty: The LingQ library isn’t really helpful, mainly as it isn’t really organized, like most of the software. So you may find some helpful stuff as a complete beginner, but soon will be much better of importing your own content. It’s my impression that the majority does it like that.
If you haven’t noticed any odd behaviour after the crash, you should be good to go. And if problems should occour, their is a customer service you can reach out to. But I highly doubt this to be the case, so no worries (again 
).