“Generically medieval”, by which we mean our peerage is French, our castles are German, our weapons are Italian, and everybody speaks English.
you can have religion in one of 2 flavors: “woo hoo aesthetic garnish” and “Sinister State Control in Bad Allegory for Problems in Modern Christianity”
Also, the latter is aesthetically French Catholic, theologically German Protestant, and has the institutional structure of the Church of Scientology.
not to mention that this land is simultaneously inhabited by thinly modified northern vikings (Nordic pre-medieval/9th century), travelling mongols (European medieval/13th century) and a wealthy italian merchant family with a house full of oil paintings (Southern European renaissance/15th century). the dance of the day is waltz (refined German 18th century country dance).
But it will only actually be called inaccurate if an adaptation chooses to add a Black person.