In the cold open, when Sweetie Bell burns breakfast, we hear a beeping like a smoke alarm, and nearer the end of the episode we hear the same again when Sweetie Bell burns more cooking. If we were, just momentarily, to assume this wasn't just a thematically-appropriate sound effect, I think you probably could in this world invent some sort of smoke detector with magic, and it would be one of the more important inventions to make in this world. Fires were a scourge before the modern era, with so many buildings being made of wood and other flammables, and with relatively ineffective fire-fighting. They were incredibly difficult to keep from spreading, which is part of why the US firebombing of Japan, a country that still at that time had mostly wooden structures populating it, was so incredibly destructive. So, something like this would be incredibly important for the semi-renaissance world of Equestria - I would be prepared to accept either explanation, that it is a smoke alarm or that it is just an illustrative sound effect.

Rarity and Sweetie Belle's parents humour Sweetie Belle's efforts at cooking breakfast in a way that strikes me as potentially good parenting. They give positive encouragement of her efforts, which is great, although she could perhaps use some constructive criticism. And like her older sister, Sweetie Belle packs quite a lot of luggage! As Rarity prepares a new breakfast herself, Sweetie Belle becomes increasingly desperate to help out. A curious thing with children is that they have this desire to help and to 'really' help, yet they don't quite seem to understand that finding a way for them to 'help' actually, usually, just increases the length and difficulty of the task with an additional vector. It is awkward to sit and wait, however, and with some skill it's possible to make people feel as though they are helping out (although in such cases they are almost always, in fact, doing precisely the opposite). I think the real complaint is not that they are not being 'of help', but rather, that they are not being included, and that they feel left out. This very much seems to be Sweetie Belle's issue this episode, and it's appropriate that as a child, she struggles to articulate that beyond wanting to help.

On the other hand, Rarity doesn't realise that all these problems Sweetie Belle is causing for her are just stemming from Sweetie Belle being desperate to spend time with her. It's difficult because Rarity is working hard at her job, but ultimately it would probably be worth the investment of some time with Sweetie Belle just so she'd be content enough to not run around looking for things to do and inevitably ruin something in the process. Sweetie Belle also expresses being bored, so having something to do together and something for Sweetie Belle to do on her own would have worked a treat, and further, Sweetie Belle is actually a fairly undemanding child in this regard, she does not seem especially picky about what activities she'd want to do. It wouldn't be too difficult to come up with something, although again, it would inevitably require some time, which takes away from Rarity's work. Interestingly, this almost makes it seem as though her parents are better with Sweetie Belle than with her. It is a little unfair, when they know their daughter runs her own business, to arrive without announcement to drop Sweetie Belle off, before Rarity's even woken up no less, and let Sweetie Belle run amok in their daughter's kitchen without permission from Rarity first. At the very least they haven't made things any easier.