I have yet to see anyone reproduce a flag close to the original. Very few can reproduce the stitch count, except for me of course. I do mean to brag on my own work as I have not found anyone else who can match the quality. You must consider though that back in the day they didn't have pictures or the internet to see what it would look like to make their own version of the flag, they had a description set down of what the flag was suppose to look like and the flag maker made the flag to the description given, that's why there are several different versions of the flag.
Example: The first national confederate flag has 2 red bars and 1 whit bar with 7/13 stars on a blue canton. All of the first nationals that were made fit this description but yet some included symbols inside those stars to make them seperate from other states, they customized them so to speak.
If you are making yourself a flag or flags I wish you the best of luck. I handsew all of my work and I can tell you that a person must have a strong mindset when doing this. You must keep the vision of the completed flag your making at the front of your thoughts the entire time your working on it. See yourself showing it to others, see it flying high on the flag pole. Positive thoughts are the key to completing a project. Start small and work your way up.
Here is an example of a flag I made from measurements from the Museum of the Confederacy in Richmond,Virginia for a gentleman portraying Gen. Jubal Early:
Good luck !