>>3333972That's a (her) problem unfortunately, and it also answers the question as to why she often seems to be able to do tricky sections just fine before proceeding to fail at the most basic of jumps.
Beyond performance anxiety though I think it's highly dependent on how much she's enjoying the game itself. Galaxy is an easier game compared to Sunshine but it had its fair share of optional challenging missions that she got through with actual patience and reflection on her mistakes (bar purple coins), and if you go back to that one it's night and day how invested she was in Galaxy. (It also helps that Galaxy controls well, so for most of her mistakes she had only herself to blame.)