This problem isn’t specific to Portuguese. Some languages are incredibly hard to find, my guess is that they were printed less and on top of that very few people had a desire to keep them.
There was a recent post about Dutch Unlimited Fossil where people are experiencing the same thing. Even across all of the people that have interacted with that post, there are still cards that nobody has images of. It’s hard to find cards for sale when the largest collectors in the hobby don’t even have copies or photographic proof that they exist 