I do agree on the problem.
The language auto detection is a very nice thing but whenever I get used to something I tend to forget to check if it is correct, especially in the case of "Portuguese" and "Portuguese (Brazilian)" it is very easy to overlook that difference.
So the fact, that I still can manually change the selected language doesn't really help me when my brain is refusing to remember to check first the correctness of the information befor clicking on the upload button.
But, firstly, I like the auto detection and wouldn't like to turn that feature off. I would need a checkbox to confirm the language that was auto-detected at the most (which would be much faster than to select the language from the dropdown menue).
Secondly, I have difficutlies to imagine that it is "hard for a software" to auto-detect the difference between the "old" and "new" Portuguese
Since there are so many keywords on one hand (such as the abundant/rar usage of "você" and tons of other rather clearly favored words, such as "autocarro" vs "ônibus", "carona" vs "boleia", "faz favor" vs "por favor", "fix" vs "legal", etc. etc...) and there is such an incredible expertise behind opensubtitle.org on the other hand, I believe it is not so hard to find something that brings a >99% accuracy to the autodetection function.
Of course, this probably would be task # 7,257 on the list of our devoted developer at Opensubtitles.org, and therefor I wouldn't dare to request such a thing, especially since I'm really enjoing the new Subdownloader 1.2.4.
But maybe one day....