Learn Croatian: Premda imamo kvar, moramo ustrajati. - Although we have a malfunction, we must persist.

Yes! Premda, mada, and iako all mean "although" or "even though" and are completely interchangeable here. While iako is the most common in everyday speech, using premda adds nice variety to your vocabulary and works exactly the same way.

Kvar (malfunction) is the direct object of the verb imamo, so why doesn't its ending change for the accusative case?

Kvar is a masculine inanimate noun. In Croatian, masculine nouns that do not represent living beings have an accusative form that is completely identical to their nominative (dictionary) form. Therefore, it takes no special ending here.

Why are there no words for "we" in this sentence?

The pronouns are dropped because the verb endings in imamo and moramo (the -mo suffix) already tell us the subject is "we". Adding mi (we) would sound unnaturally repetitive unless you needed to strongly emphasize who had the malfunction.

Why do we use the infinitive ustrajati (to persist) after moramo instead of a "da" structure?