Historical fiction written as historical fiction: Georgette Heyer writing about the Regency, a century or more past her own time.
Then there's Jane Austen writing about her own time... but it's historical for US.
Jane Austen will -- being steeped in it-- probably be faithfully representing the culture and especially language as she perceives it. But she will be blinkered by a narrow perspective and of course the lack of ability to research different viewpoints or see what happens after her own time.
Historical fiction-- greater context, more distance, more understanding of the causes and effects. But the colloquialism of the language might be suspect-- replicating conversations which were not "heard".