no, that's correct. You can not get a normal redshirt if you play one down.
A redshirt is the term applied to a player they does not play in any games that year*for whatever reason*(medical, developmental, grades, whatever).*You have 5 years from when your clock starts (for almost all softball players this occurs when they attend their first class in the fall) to use 4 years of eligibility. A player uses that year of eligibility as soon as they go into a game (even one at bat or one pinch run in a fall game).
A medical hardship waiver (often called a medical redshirt) is the term for getting a year or eligibility back due to injury. There are several things that have to be met but, in general, here*are the basics:
the injury must occur in the the first half of the season
the athlete cannot have participated in more than 30% of the games
the athlete cannot be ready to return to full participation before the end of the season (so, yes, in katyite's daughter's case, she would still be able to take batting practice; if she is not able to throw, that would not be considered full participation);*[A big issue with this is when coaches don't understand the rule and say, well they have lost almost the whole season, so I just won't play them and try to get the year back. If the medical records say they are cleared for full participation, it doesn't matter if they play, they do not meet the criteria.]