Only b/c you've made the error several times now: the language is Parseltongue, one who speaks it is a Parselmouth. Thus, Harry and Ginny are Parselmouths, not Parseltongues.
Author's response
Thank you for the comment!
I'll try to fix that.
Ok, I think I've fixed all the instances of that across all four chapters. If you spot any I've missed let me know where.