A great article from soccer parenting magazine on limitations v. mistakes. Mistakes are within a keepers control...on the one hand, they shouldn't be making them-- on the other hand, they all will because that's how they learn. Limitations are more tricky and require long term development and body growth....a 9 year old keeper is unlikely to stop the PK in a full goal high and to the corner no matter how hard they try. My problem: it often seems like we're running around playing whack-a-mole with mistakes which pop up, leaving less time for long term development.
https://www.soccerparenting.com/mistakes-vs-limitations-youth-goalkeeper/
https://www.soccerparenting.com/mistakes-vs-limitations-youth-goalkeeper/