I think you missed the point of jacquesm's comment: "They are also tracking them quite well so don't compare them to let's say Romania or Bulgaria where tracking is next to non-existent."
In other words, it's highly likely that Romania didn't "do better" than Portugal, but rather they're doing a very poor job tracking overdoses at all.
The data points don't even have error bars, unfortunately. They come through various filters. Leaving out one government's reported numbers and keeping another's is a political decision in itself, so it's best to just report the numbers and warn readers of their veracity.
In other words, it's highly likely that Romania didn't "do better" than Portugal, but rather they're doing a very poor job tracking overdoses at all.