Learn Spanish (Latin America): Ojalá la juventud y la belleza nunca terminaran.

We use the imperfect subjunctive (terminaran) with ojalá to express a wish that is impossible or very unlikely to happen in the present or future. Since youth and beauty ending is a fact of life, wishing they wouldn't end is an "unreal" wish. If we used the present subjunctive (terminen), it would mean we think there is a real, realistic possibility that they won't end.

Is it wrong to say ojalá que instead of just ojalá in this sentence?

Not at all! You can use either ojalá or ojalá que here. Both are perfectly correct and mean the same thing ("if only" or "I wish"). Adding que is very common in everyday speech, while dropping it can sometimes sound just a tiny bit more formal or poetic, but they are interchangeable.

Why are the articles la included before juventud and belleza? The English translation doesn't say "the youth and the beauty."

In Spanish, when you are talking about abstract concepts or nouns in a general, universal sense (like youth, beauty, love, or time), you almost always need to use the definite article (el, la, los, or las). English usually drops the article in these cases, but Spanish requires it to introduce the subject.

I've seen the imperfect subjunctive end in -sen instead of -ran. Could I use here?