Hi!
I’ve built a very similar if not same process. 400 words shouldn’t be a problem for metadata, but even so. Look at the documents you have and try to discern if you can split them up somehow. If you have law documents - split them by Articles of that law and inserts each article as its own document. If you have court cases, check if it would even be good to push the whole text. Maybe each paragraph writes about a different aspect of the case, should it all be joined into one vector? Could you split them up into smaller meaningful documents.
Good luck.