I think it makes sense to elaborate your points a bit more in the work experience section now that you do not have the further opportunity to so so in the personal statement. You could, when appropriate, draw links as to how some experience developed your interest in commercial law, or in a particular practice area the firm excels in. You could also just explain how it led to the formation of relevant skills. Nonetheless, you should do so sparingly, as you do not want all your work experience entires to sound repetitive or to seem like you are clearly trying to circumvent the firm's choice to drop the written motivational question element from the application form.
Is the test automatic?Freshfield's confirmed via a pre-launch webinar thingy that I attended the other day that they have changed the application process quite significantly. Instead of long answer questions, there is only an initial application form with work experience etc and then an online assessment (which I believe is like a mix of critical reasoning and SJT type questions with a few video questions thrown in as well) and then, if successful, an AC. They have a preparation portal on their early careers website (like Hogan Lovells) and the whole thing is ran by Cappfinity I believe.