So if I learned Koine Greek would I be able to read Byzantine Greek?
Well it'd be a different style probably I'm guessing, Biblical Latin is so different in Syntax from Cicero and Caesar, so simple, while Cicero and Caesar can store such huge number of clauses in a single sentence, even making each sentence 50-100 words long, and so many more amazing grammatical skills.
Indirect Clauses have a different style
like the use of the conjunction «that» would be said differently classically.
James 1:3 γινώσκοντες ὅτι τὸ δοκίμιον ὑμῶν τῆς πίστεως κατεργάζεται ὑπομονήν.
3 scientes quod probatio fidei vestrae patientiam operatur
3 Knowing this, that the trying of your faith worketh patience.
since I don't know Greek, I'll use Latin to show you the classical indirect style of stating things.
The Classical Translation of this verse is:
Scientes probationem fidei vestrae patientiam operari.
Knowing the trying of your faith to work patience.
We appreciate the Classical form because it's clearer, clearly shown in this example.
They believe that they're good, They believe them to be good (others)
they believe that they're good, they believe themselves to be good (themselves)
In the popular syntax, we have no idea of who's they, themselves or some other people.
But in the classical we know very clearly.