aftermath

I thought the existing translation missed a lot of the nuance in the song, so I made an account to submit my own. I still wanted to preserve the ambiguity of the original where appropriate, though, and as such decided not to connect many of the lines, but sometimes this was simply not possible without sounding strange or unnatural. Ergo, the following paragraphs are what I thought you should know about the calls I specifically made:

"色は死へ" literally translates as something like "colours death to", with "へ" marking the destination of a movement or process, in this case 'death'. The word "to fade" isn't actually in there, but a change in the colours towards 'death' is implied, so I felt it fitting.

In “[...] 安らぎとは貴方と観る揺らぐ花”, a specific Kanji is used for “みる”, “to look”, which is usually spelt “見る”. The character used here specifically refers to obeserving scenery.

Near the end, the sentence "[...] 似せた夢抱いては　/　砂の城と優美な死を" is indeed implied to be linked in Japanese due to the particle "は"; only the last part which would usually contain the predicate (i.e. the main verb) is omitted, leaving the end of the song open to imagination.
However, this translates very poorly into English since the verb would have to go before "a sandcastle". I decided to denote it as two cut-off phrases for that reason; just know that they're probably supposed to be connected.

Also, I sometimes inserted "you" in English where just putting an article would have sounded strange, but something like "髪を撫でる" might just as well refer to the narrator themselves, even though I find it unlikely in the context of the song.