"There were two right shoes and four left ones there."
Translation:Byly tam dvě pravé boty a čtyři levé.
The natural way to say this in Czech (unfortunately unaccepted now) is "Byly tam dvě pravé a čtyři levé boty." In English, the natural way is to use a noun for its first occurrence and pronouns later, in Czech it is vice versa, the noun should be in the last case the object is mentioned in the sentence, and before the object is signalled by omission of the noun before "a" or the comma. Current "correct translation" sounds less unnatural than "there were two right ones and four left shoes there" would in English, but it still sounds clumsy. Perhaps it should be kept as acceptable, but not as preferred.
It is a pretty strange place for it. It would make it the point of the message, the most stressed piece of information. It doesn't make good sense here. If you were speaking about some particular shoes and the information is that they are there, it is absolutely fine to say "Ty boty jsou tam.". But when informing about kinds of shoes that were there it doesn't make sense. The main information here are the shoes, not the place.