Confirmation email needs to contain the conference name and location
"Thank you for registering for DebConf19" -> "Thank you for registering for DebConf19 in Curitiba, Brazil, 2019." Otherwise this is not helpful as a proof to visa officers as per @mwei 's email. The dates are given inside the email body under "Food" and "Accommodation" so probably it is fine to not also add them to the intro text. But if it's easy to do, please consider adding the dates (incl. DebCamp) to the intro line as well.