I see that you translated the French quotations at Homo erectus and Homo sapiens sapiens (note that this quotation is also at Homines sapientes sapientes). I think if the original text uses the plural Homines erecti (and Homines sapientes sapientes), then it should not be changed to the singular (Homo Erectus; also note that erectus should not be capitalized) in the translation.
You have a point about the capitalisation, but I disagree with the plural on linguistic terms: translingual terms often find themselves subjected to the grammar of the language in whose context they find themselves. And the standard English usage for Species names is to treat them as indeclinable. A google search for "these homines erecti" or "those ..." results in no hits at all. Which isn't a hugely scientific test, but "these homo erectus" or "those homo sapiens sapiens", where the species is treated as a plural noun (as opposed to an adjective or an attributive noun phrase, as in "these homo erectus fossils" or the like) are plentiful in websites, books, and scientific papers.
I submit that the normal English usage is that Homo sapiens sapiens and Homo erectus are indeclinable.