If her round off and back tumbling is good, you can train yurchenko. This can be as simple as if they can back tumble in a straight line. If they go crooked, that's not gonna work.
For tsuk, you should have mastered a decent handspring. It's just another way to go if you're not really going to go towards handspring front vaults.
Did she only compete a front handspring in L8 and that is why her scores were so, well mid 8's? ( handspring isn't worth much, but handspring full can be tough to land well)
You say her handsprings were just ok? Were they ok, or do they have a nice float and good pop off the table. No bent arms or limbering off the table ( I hope a L8 isn't doing that like a 5 ). I'm really only concerned as to how much power she has in the run, off the board and table. As for form or landing errors, that's not the issue here.
How is her round off in any case since you still have to be able to block well to set up for the flip or handspring.
Generally, tsuk is learned before yurchenko, but many gyms well start yurchenko drills in compulsories as simple as round off the board and run, punch, round off. A good compulsory could do this in 4 or 5, but by 6 they should be able to work on that. They might not get towards doing round off back whip or back tuck/lay until they have those skills in 6 or 7.