I buy all my bikes used - a couple decades old at least - and the one thing I've noticed is that the ones with grip shifters seem to work pretty well, whereas the ones with trigger shifters almost always dont shift right anymore. Trigger shifters are great - when everything works as it should, but due to the design they just seem to wear out much quicker. Even the top of the line versions dont seem to last.
So yeah, I think your daughter will do just fine with the grip shifters.