"Kateřina kupuje pro svého manžela nový oblek."

Translation: Kateřina is buying a new suit for her husband.

[Drakunia]

Why "Katerina is buying for her husband a new suit" is not accepted?

[SRChess]

According to "The Soul of Grammar" by Sonnenshein, English expects a word order of Subject-verb-indirect object-direct object, for example, "she gave me a book". If the order is changed a preposition must be used to indicate the dative case usage, e.g., "she gave a book to me". It would be incorrect to use the preposition if you use the word order to indicate dative usage. Saying "she gave to me a book" is not really correct. So "Kateřina is buying her husband a new suit" ought to be accepted. I did not check to see if it is or not.

[BoneheadBass]

That is a very nice literal translation, but it is unlikely to be used in speech or in writing. It is not grammatically incorrect, but it's not the normal word order for native English speakers.

[2200Lucia60]

Kateřina buys a new suit for her husband. Accepted (now). It means she is gone away, shopping. But you don't see her doing the action. (There's no necessity for it to be an habitual action)

[BrianG1941]

As an englishman I do not find it a strange word order at all. It seems perfectly OK to me and I would tend to use this order automatically.