One major thing I can agree with is leave the coaching to the coach. It is wonderful you are involved and I am sure it means a lot to your daughter, but be very careful. If you are paying an instructor you must trust their ability and judgment on developing your daughter’s pitching skills. If he or she is a good instructor they will let them know what they need to work on and give her homework.
When parents correct there can be 3 main problems:
1. Pitchers need to learn to self correct which is typically experimented with during practice. When you point out what she is doing wrong it takes the development of this necessary skill away. You could help with the direction sometimes (i.e: remember what your coach said about high pitches? or I can't remember what your coach said about high pitches. Do you remember? Etc. You can even act like you learned something when she remembers

) but try not to point it out.
2. A good coach will not point out more than a couple of things at a time to work on. You may notice something else she is doing wrong (which is good to make sure the instructor is on the same page). However it can set practice back if she is focusing on too many things.
3. Let the coach be the coach and you can enjoy catching and being Dad. I can’t stress this enough. A young woman wants and NEEDs positive feedback from a father. Often times girls will only hear the criticism even if you told her 10 things she did right she may only remember the one thing you told her she was doing wrong. This is one of the major differences in male vs. female athletes. (There are always outliers but this is true for many) I am currently conducting a research experiment with a University on female athlete burnout. One of the major reasons we come across all the time is issues in the father-daughter/mother-daughter relationships that “it wasn’t fun anymore” because the parent was too involved and they felt they could “never do anything right.” Etc.
I’m not saying you should NEVER correct but try to keep it to a minimum and give lots of positive feedback.