It can only mean shortage in the singular. So Bristen på … would clearly be about shortage of something, but when you say bristerna, it does indeed mean the flaws, shortcomings etc.
This is just a guess, but I wonder if Swedish doesn't really talk about plural shortages, and perhaps something like "The water shortages in several parts of southern Europe are severe" would naturally translate to "Vattenbristen i flera delar av södra Europa är allvarlig".
I was wondering more about if you had shortages in multiple things like the rationing during WWII.
They're both OK I think, faults was already accepted but I'll add defects. I feel shortcomings is possibly the closest counterpart after all, in bristerna there's a feeling of quality lacking, rather than being damaged. (fel and defekter are probably closer to faults and defects).
I do not see the conclusive answer to question about how is 'shortages' in Swedish.