Vegeta dodges a couple times, then Tempest gets annoyed, TKs him, and smacks him with a bomb. She's not dumb enough to waste energy or bombs on a target that'll keep dodging, she only has a maximum of four bombs at once (The most she's shown to have at once). She's not going to blindly waste them hoping they'll hit once she runs low. Tempest can also just forcefield and let him waste energy on that.
Some may question the viability of her range due to her profile, but her profile is hilariously inaccurate in that regard. It claims her range is several meters without a calculation, and ignores the way
she aided in defending the Mane 6 with her magic from very far away, as well as the fact that less skilled characters consistently show much farther magic range.
Another notable thing here is the people she scales to. Celestia's magic is so powerful that a device embued with a fraction of her power can replicate her feat. I don't know by how much Vegeta can increase his power, but considering Tempest scales to people who are already borderline twice his power, adding the above info to the mix just makes the gap that much bigger.