There was a feature request to make all these subsites multilangual, https://forum.inaturalist.org/t/support-all-languages-on-inaturalist-network-homepages/25907 but it is dismissed. Some of the sites are, some are not…
These are the links you asked for:
https://www.argentinat.org/set_locale?locale=es
https://www.argentinat.org/?locale=es