Por quê "long letters" foi traduzindo como "cartas antigas"?

Por quê não "cartas longas"?

I'm trying to unfold this album with my own various contents that I've been thinking of since long time ago. 

Although I hope everyone likes it, or sort of with a refreshing mind "what if not? What can we do?". I'll come back tomorrow with a confident mind to see if there's not even one out of 10 Blues that you like. I'm sending you my long letters with my same expressions and bodily gestures, however with a bit more refined/filtered and dashing frequency.

I'd be grateful if you could cherish/treasure it.

Hoping these songs/music are not just reckless courage

But that they're the confidence that you guys gave me.