I don't know how helpful absolute statements like that really are. Even in the writings of Caesar, which of the classical writers hue closest to the order you outlined, one sentence in six does not end with the verb, and a quarter of those that do put the verb last show the object before the subject, and presumably many more in some other way deviate from that pattern. In the writings of Cicero, fewer than half of the sentences end with the verb.
It's all right.
The classical prose writers, who have generally served us as our models for good Latin style, tend to avoid ending a sentence with an adverb or adverbial expression, so you will struggle to find sentences structured that way in the works of Cicero, Caesar, Livy, and so on.
In the pre-classical comedies of Terence and Plautus, however, such examples abound (a quick search turned up around 20 sentences ending with "domi"), and in fact it is on these authors that many of these short, colloquial sentences that we are working with on Duolingo seem to be modelled.
So-called "proper" English is also a dialect. There is no such thing as not a dialect, regardless of which language we're talking about. So-called "proper" English is just the standard dialect of whichever English-speaking country you're in. Standard British English is different from Standard American English is different from Standard Australian English. Standard French of France is different from Standard French of Québec. None are better than the others.
A standard dialect is nothing more than a dialect that acquired a high status. It is also called the prestige dialect. All dialects have their own histories of development and none are "just the standard dialect with errors".
Oh goodness, I never learned that case! Good to know. So domi is just the locative form of the second declension noun (as I remember it) domus, domi? If you don't mind me asking, to change a noun that fits the criteria to locative, would one just make the ending 'i' or is it declension dependent?