Ok, lemme quickly explain this song.
To my understanding, this song is about a woman/man who fell in love with a person, but because of reasons couldn't say "I love you" to his/her lover in person, so the narrator decided to write a love letter in the form of this song.
The chorus of the song is kinda saying like I really love you, but I don't have the guts to say it; in the end, when I was thinking about you (how you would feel when you open the love letter"猜你启封的表情"), I had the courage to write down "To my dearest lover:" (as in the start of a letter).
This start of the letter may be what confused you, the word choice is not exactly as what we write in Chinese （but we kinda understand）. 致你 I believe as in like 致我最亲爱的人 at the start of the letter, or like "Dear XXXX" in English, or perhaps 致XXX on the envelope.
If one were to directly translate, then I believe the translation is mostly correct but certain parts of it are very correct (like the typewriter part).
I'll just quickly give you a brief idea of the song's meaning:
So from "恋恋不舍" to "不知去往何方", I love this person, who is filling the void of my loneliness, I dunno how to express my love.
From "支离破碎" to "不经意的设防", I've been hurt before, I am a little defensive so I can't directly express my love.
"跌跌宕宕" to "穿梭在无人演出的剧场": I keep thinking about you in my head.
"若想念是凋谢的云" to "写不出 会别离 太爱你": I have a crush on you. (Silently whisper like the clouds in a wind or a jammed typewriter that couldn't type the love letter)
"到最后" to "只敢写下开篇的 致你": So in the end, I could only think about how happy you'll be (despite not knowing how the other might react)) and then start my love letter
