I also think we're seeing two time-periods
Past time period:
Henry loving Finis and getting killed by her, via Rudo tricking her, and her destruction of the world (the cost is her immortality and/or frozen time / time-loop)
Finis also is losing her life as a cost of her power of songs (until she destroys the world)
Henry is within the Gilt miltary, but is seeing its corruption and abuse (mainly rudo), but he's not a traitor, leaving the military, and openly rebelling against it yet as seen in the future with rin
Corte gets killed by rudo, using her own poison that she had tried to use on rudo, so that finis and henry could be free of his evil truly finally, but unfortunately, he knows poison well
Bazra (?I think?) isn't the commander of the entire military of Gilt
Also, do we see Alea in the orchestra or outside of it at all?
Also, do we see Al's father Hawkray at all?
Henry's family is well known as respected, and he's well known
His sword is known to be special, I think (or was this in the future time, meh, would have to re-watch this anime a few times and carefully make notes, as this is quite complex time-period event stuff, lol)
Everyone knows finis, everyone knows what she looks like and has seen her
There doesn't seem to be any mentioning of general hawkray
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In the future time period:
Henry loves Alea
No one seems to know finis at all (well, they know of her, but no one's ever actually seen her), including henry
Corte is seen alive (I think, or was this just merely after rin and finis sang together, meh, can't remember if we saw corte at all before the sang and rin disappeared, meh)
Finis seems to be able to use her power without any cost to her life, and she openly kills with her power and is joined with Bazra (no rudo to be seen, I think), as we understand her pain from having killed henry, and wants to end her suffering of immortality, taking the whole evil world and its people with her, ending it all
Does Rudo even exist? was it the same prince rudo, or did the prince look different, with blond hair (not rudo?, who got dark hair)? when bazra attacked the gilt palace, wanting to kill the king and prince, wanting to rule gilt and the world himself, with the sound machine
Henry doesn't seem to be known, like he was in the past, at least not by the mercenaries, not sure if he was ever known by the gilt military or not, as he's openly fighting against them and bazra, which results in bazra freezing his leg, with rin finding him and healing his frozen leg
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Also...
I think it's likely... that time has been looped through a bunch of cycles... like the past time period got effected from having happened multiple times, I think finis has been looping in time multiple times, and not just once... there just seems to be some influence from many loops having already occurred...
As finis created the entire legend of the songs... which then became part of the past's and future's time periods legends.... this suggests that poor finis has had everything we've seen, both past and future, happen many times for her....
Which gets into... was there rin in all of these multiple loops of the future... or was this "to be last" loop of the future, the only time that the future had rin? or has there always been rin? but then why wouldn't the time loop have already been broken? or does it ever actually ever get unbroken? is everything still repeating, or has the loop been broken finally?