Let’s say I’m reading Text A and highlight the word “la casa” as a new word. It gets added to the list for Text A. Later, I read Text B and come across “la casa” again. Currently, it’s highlighted, but not added to the list for Text B. In this way, when you choose to practice from specific books, it does not make sense as the list is not complete. It seems unlogical, isn’t it?
So I suggest that when you first open a new text, its vocabulary list would automatically shows all new words (instead of just being highlighted in the text), which have been added to vocabulary lists of other texts, like the way Lingq does.