Thank you for your understanding! I do think that there probably would be a cost to add every language that is not fan-translated! As far as I know, I think many of the 8 official languages that are translated were actually done by very dedicated fan volunteers (and even one of our voice actors [the amazing LetyDoesStuff] helps regularly with the Spanish translation)!
We really appreciate your care, interest, and feedback! I am not sure how languages are decided, and I am not sure if there are any current plans to add more officially-funded translations to the game right now. Sorry I can't provide more information (I just handle community management, not any translation knowledge or decisions) but I'll be sure to mention your feelings about Portuguese to the team!
We understand that you'd like to make more videos about House Party and would like a better translation for your audience - and we'll be sure to keep that in mind. Thanks again for your care for House Party, and we hope you have a happy holiday! :)