Disorder

Strongly pierced light and, front-back's shadow and — both nouns marked with と (and), suspended without a verb. Lyric sentence-fragment style.

裏表 ('reverse-and-front') is the Japanese word for 'two-sided / two-faced' — used both literally (the two sides of paper) and figuratively (two-faced people, hidden second nature). For SAO it nods at GGO's gunfighting underworld vs. the player's everyday self.

Cut-loose intention/belief even — 〜たつもり means 'in the belief that one did' (often with implication that the belief is wrong).

切り離す ('cut-and-separate') is a compound verb of physical and emotional severing. つもり after a past verb is the 'I thought I had…' construction — heavy with self-doubt and unreliable narrators.

no one knows + god + can't become

GGO's setting — anonymous gunfighters online — explains 'a god no one is supposed to know'. The protagonist Llenn is a tiny pink shooter no one expects to be lethal. Becoming legendary while staying unknown is the franchise's tension.

This-eye in be-reflected (nominalizer-の) (topic), lie-things with smeared world — の after 映る nominalizes the verb clause.

まみれる is a vivid verb — covered with something messy: blood (血まみれ), mud (泥まみれ), dust (汗まみれ). Applied to lies (嘘まみれ), it makes the world feel sticky and unclean.

Fleeting's dream (obj) expose to let-go — 暴く is a literary verb meaning 'unveil / dig up / reveal what was hidden'.

暴く is the verb you use for digging up graves, exposing scandals, ripping open secrets. Combined with かりそめの夢 ('fleeting dream'), the line is more violent than 'wake up the dream' — it's 'rip the dream open'.

That instinct (subj) guides as-(adverbial) go, ash become until — 〜ままに with a verb means 'as (the verb) does / unchanged from how (the verb) is happening'.

灰になる ('become ashes') is a defiant J-rock image of giving everything until total burnout. Compare boxing manga 'Ashita no Joe' / 'Tomorrow's Joe' where the protagonist literally burns himself white in the final panel.

Stay-(te) can-obtain thing such-as not-exist because, believe-should thing copula — 〜べき is the modal-deontic 'should'.

信じるべきもの ('thing one should believe') uses べき, the formal/literary 'should/must' modal — found in editorials, sermons, and philosophical-tone J-rock lyrics.

Dressed-up that dress (obj) tear-off to let-go — 剥ぎ取る = 剥ぐ (peel off) + 取る (take), forming 'rip off and remove'.

Stripping the 'ornate dress' off truth (or off the world) is a recurring revolutionary lyric image — the same energy as 'unmask the lie'. ReoNa often pairs feminine surface imagery with destruction verbs for that disorder aesthetic.