賛歌 is a not very old word used nearly exclusively to describe Catholic hymns (praising god, describing the Eucharist, etc). I’m surprised he’s using such a culturally Western topic to sing about (maybe the album is a Western concept album). 彩(り) means a range of colors, and non-literally is used to mean the “spice” to something. Adding “彩（り）” to a song would be to spice it up with various meanings and colorful language.
When he say’s 光 it likely means the light of god, or little less likely Heaven. The first half presents the speaker who has just murdered (or metaphor of such), and second is him wondering about people turning to god.

Maybe you did it too literally without understanding the reversed lyrics (we do it in English songs too for effect) and grammar.
痛めつけて膿む瑕口を涙で隠してみても
治りが遅くなる　だけ顔を挙げて
Trying to cure the flawed openings that had formed, hiding my tears back
Though recovery itself is too late, I raise my face skywards

Should be more like:
Even though I try to hide the festering hole (puncture wound!) that taunts me with tears
The recovery comes just… too late. I turn my face towards the sky (lying on the ground so can’t raise his head).

Then it goes into how his prayer’s sprout from the ground to the shining heavens.When people do not take care, sometimes they lose something important (like their life).

Yadda yadda yadda
The light (of heaven/at the end of the tunnel/”please caroline don’t go into the light” kinda light) is far away.
The light tenderly approaches me.

He’s dying, horribly, talks about loneliness (except if you have God, then never alone), etc etc.

As a suggestion, try not to add expressions which aren’t expressively added into the song and affect grammar (i.e. “likes to be” is never stated and changes meaning considerably). Also, it helps (me at least) to read the whole thing a few times and grasp the topic first, as every phrase will relate and refer to the topic (dying guy + “Praising Hymn of Various Colors”)
And especially for Kagrra, a lot of their songs are a “scene” from a novel, so try to imagine what the scene is, character, environment, sound, colors… This one especially brings to mind a few Akutagawa stories.

Hope that helps your future endeavors. I don’t really have the time for the same!