I think this section answers a lot of your questions

Only one in 10 of the more than 20,000 children tried as adults in Florida were given juvenile sanctions and less than 5% received a “youthful offender” designation, the Herald found in an analysis of the last 15 years of state court system sentencing data from 2008 to 2022.

Children tried as adults were sentenced to a little more than three years in prison on average for third-degree felonies — around 50% longer than the average sentence given to adults for the same class of offense. The vast majority of all felony charges are third-degree offenses, which are the lowest class of felony crimes and include burglary, some types of assault, drug possession and certain DUI offenses.

Children and adults had similar average sentences for more serious offenses that fall under first and second-degree felonies. Overall, a child tried as an adult was sentenced to a little more than five years for a felony charge while an adult received around three-and-a-half years. These trends held even after the Herald adjusted for the most extreme sentences that could skew the figures.

is it really so bad that a small number of the worst offenders

They’re not necessarily “the worst,” prosecutors can try any juvenile as an adult that they want to in Florida

Is it really fair to compare sentences of a small number of the worst offenders to sentences of the general population?

They’re comparing juveniles and adults charged with the same class of crimes, and actually the disparity is more pronounced with the lowest level third degree felonies than with the first and second degree ones.