I've been coaching HS varsity and travel for 18 years, however I am not a pitching instructor! Having made that qualification, I have to say that what struck me about this thread was not the lefty/righty screwup, but the pitches! You've got an 11 y/o kid and her pitching coach is calling for her curve ball and her screwball? Really?
When I'm evaluating new pitchers at tryouts, and I ask them what pitches they throw and they start giving me a laundry list of advanced pitches, I mentally "roll my eyes" at them. Yeh, sure. Much more often than not, the pitches all look the same, and they're not breaking anywhere! There are way too many "pitching coaches" who are stealing money. I understand that they're under pressure from the parents to show their little darling 5 or 6 pitches, so they can tell people they have 5 or 6 pitches. But I don't count it as a usable pitch unless she can make it go where she wants it to go. Show me an 11 y/o who can hit her spots consistently, change speeds while still hitting spots, and maybe throw in a drop, and I'm taking that kid!
I know there are some exceptional kids out there who can do that, but I've got to tell you that the great majority can not. If I had a $1 bet on each 12U pitcher who claimed she had multiple pitches but who really didn't, I'd be a rich man with the money I won off those who didn't.
Amen to there are WAY TOO many PC's out there. And most are under qualified. I taught my DD to pitch from 8YO. At 10 we went to a PC ( that has/had a gold level team ) because I come from a baseball background and thought the PC might have some "magic dust" to help us progress. After a month of the lessons we quit using her. And never used a PC or HC again. There was NOTHING she did for us that we didn't already know or could figure out with time and practice. I think most are a money racket.
Now here is my thoughts on curves/screws for 10-11-12YO's. I started s-l-o-w-l-y letting my DD throw them in games. Did they break at 10-11? No. But she needed to learn the release and motion of the pitch. Just as each year she got faster MPH, she also gained thread revolutions and break with the pitches. Now she can knock a paper cup off a table at 43' with consistency. The screw and backdoor curve are her best "K" pitches.
Just my 2 cents.