Hi, this game in Brazil was launched with PT-BR subtitles/translation (not audio, just subtitles, menu and texts).

I have the original media for it (that have the PT-BR files inside the game) and i wanna know if i could help both the GOG Preservation Program (adding an official language to be preservated) and also help many brazilians gamers that could experience the game today with PT-BR languages.
Is there a way to add these brazilian files to the official game that is being selled right now?

What should figured out first is who owns the publishing rights for the Portuguese localization. Many translated versions are unfortunately not sold on GOG because their deals do not include those right owners.

What i know its that other games was translated/launched at Brazil from the same company (formally Brasoft).
And searching something right now as you mentioned it, i discovered that Grim Fandango Remastered was made the same way (Lucasarts game, Brasoft braziilian translatiion).

So if Grim Fandango Remastered (at GOG too) received the OG Brasoft translation, i could see that could have a good chance that the same could occur with Monkey Island and other games (Dark Forces 2: Jedi Knight, example).

Some interviews about this company (that made a difference for many brazilian childs and teenagers at 1990 years with translations): https://www.overloadr.com.br/especiais/reportagens/2015/05/como-brasoft-desbravou-localizacao-de-games-brasileira-ha-quase-20-anos