I've no idea what kind of texts lawyer-linguists have to tackle, but I can say from personal experience that the texts in the translators' exam are sourced from newspapers. The subjects are always relevant to what the EU deals with: finance, banking, agriculture, etc. Hope this helps.

For lawyer-linguists: you will be asked to translate texts in totally random fields of law, you cannot make guesses based on previous exams. What is also certain is that the topics of the two translations you are required to write will be irrelevant to each other.

I totally agree its better to refer previous year law question paper just for idea, as the question of previous year is never asked and every time they have something new for the students who appear for the paper, so its better to just be ready and read everything.

I sat the lawyer-linguist test in March 2015 and the text I got was fairly accessible. It was about references for preliminary ruling and it was much easier than I expected. I prepared by reading the treaties and landmark jurisprudence of the ECJ and translating everything in my head :) - and this method turned out to be quite useful.
The text had its share of "traps" (ex. acronyms that you are also expected to know and translate) and syntax challenges, but it's overall manageable.
Fortunately, I passed the tests and they invited me to the Assessment Centre. Let's see how that goes!