The Spanish Flu most probably originated in the US, not Spain. Spain just had a pretty free press and published much about it. Never heard about the Brazilian Flu and couldn't find out when and where this was supposed to be, so can't comment here.
The question wasn't historically if the place-of-origin names were accurate. The question was if they were historically common.
I think naming diseases after places is a bad practice we should probably do away with, but it certainly has precedent. Offhand, there's also the Marburg virus. My understanding is also that it was unusual to name the Ebola virus after the nearby river instead of the nearby town.
Isn't it similar to naming medical conditions after the people that discover them? After all, it's naming pathogens after the place where there were was adequate diagnostic expertise to identify them and in which there was sufficient scientific and press freedom to report on them. And geography is obviously important in the context of epidemics/pandemics. No country or locality should receive special treatment in this regard, but much of the MSM appears to have been bought or cowed into submission by the geopolitical influence of the CCP.
