Brazilian here, I believe all your points are valid. I would say that the language barrier is the least significant issue, since most Brazilians who know and use itch have some proficiency in English (since most of the content on the platform is in English), but a translation would certainly appeal to a larger audience.
The biggest barrier is certainly the payment method; PayPal is not very well known/used here, and not everyone has access to an international credit card. I personally use PIX to pay for absolutely everything I can (games on Steam, groceries, Uber rides, taxis, bus tickets, Amazon, Aliexpress, etc), it’s simple, fast, and secure with very little bureaucracy.

