@keroro At the moment, will formatting be kept or not depends on the file you are importing. I have personally imported tons of lessons (PDF, ePUB, Word) and I do know that formatting is lost in some cases.
But not always. For example, I am importing the Mini Stories from Word File in most cases (by copy-pasting) and formatting is saved.
We are going to introduce new version of LingQ (5.0) in the near future, and it will include changes and improvements in the Reader too. All of these issues are already familiar to us, and we are working on improvements at the moment.
Not sure, however, if we are going to have bold text available, I don’t think we are going to do that.