While I have no particular grievance with SEF at the moment, I see some have had success e-mailing them for assistance.
As I don’t yet speak Portuguese, are English e-mails effective? Would it be rude to use Google translate or Deepl to translate the e-mail into Portuguese?
Just preparing as I know the day will come when I will need to contact them.
Email is not their native language. Why would you send it in English? That’s like them sending you a letter in Greek.
You gotta do what you gotta do.
Have you had success in using a language translator from English to Portuguese to e-mail SEF?
I recommend using DeepL as it has Euro PT option unlike Google.
And yes, I did test it myself with SEF, went well.
Just be prepared that their official so-called “Contact Center” is for inbound email only.
They don’t do outbound 
Joking aside, they responded only once out of six times I emailed the ‘contact center’.