As with the rest of this deck, I feel a need to compare and contrast with the RWS deck as my foundation, as I do think the Sweet Twilight can fairly be deemed "RWS-based."
There are some points of commonality between the two decks' versions of this card: both occur near water, and each feature a main figure standing in the aftermath of an apparent sword battle. Each card also depicts three people, and yet five swords, leading one to possibly wonder whether or not there were other people also taking part in this conflict who are simply no longer in the frame...?
The RWS 5 of Swords seems to indicate that the figures moving off in the background have been defeated soundly and in humiliating fashion, disarmed and sent off, and the primary character in the foreground seems to be taking mean-spirited pleasure in this.
The Sweet Twilight version is a bit different. The other two people have not been disarmed, and they also don't seem to be exactly slinking off in total abject failure: one is moving sideways to our viewpoint and is still brandishing his sword, while the other is leaning on his and kind of just gazing out to sea. Also, the main figure here -- the woman with the three faces -- doesn't seem mean-spirited or smug at all. If anything, I've always felt she looks a bit weary but exhilarated, as if she was really tested by the battle, but came out the other side of it having learned new and excellent things about herself.
I really like the point made upthread about how the three faces could possibly be a reference to Hecate -- she was a goddess granted dominion over all three of earth, sea, and sky, and both versions of this card take place at the junction point where those three realms meet.
Three main elements appear in the Sweet Twilight version of the card that have no counterparts in the RWS version:
First, there's the organ. I'm sorry to say I still don't know what to make of the seemingly random placement of such a thing so far from its natural environment...? Maybe it provided dramatic music to accompany the battle?
Second would be the birds. It's a pretty commonly held belief across multiple cultures that birds -- and very often black birds such as ravens and crows -- can act as psychopomps, ushering the souls of the newly deceased to the afterlife/underworld. My take on this card is that the birds are in fact performing that very duty here, and that the black ribbon(s) they're carrying may be the form taken for now by the souls of those who perished in this sword battle. Whether the black ribbon is actually connected to the three-faced girl at the center of the image, or is just coincidentally falling out of view behind her, I'm not sure, but the latter possibility makes more sense to me.
The third element in the Sweet Twilight card not found in its RWS counterpart would be the masks. I have this odd but strong sense that the girl in the foreground actually removed her mask from her face during the battle, and not after, thus revealing her true self to the world rather than relying on a constructed persona, and this is what enabled her to survive, and to emerge at least somewhat victorious and mostly unscathed. I say "mostly unscathed" because she does seem to have a cut across her cheek (the line is obviously bright red on my actual card, even if it doesn't show up as vividly in the scan here online). I like to think that she pushed up her mask in mid-fight even though doing so might seem risky and unorthodox, she did sustain the one gash, but then she was able to triumph by embracing and revealing her own truest self. The other combatants either died, or kept their masks on, and had to leave her in peace. There may be other interpretations, of course, but this one works for me, and it does seem to fit the image without contradicting it in any major way.
So overall, I think the card is less about the RWS' "humiliating defeat," and more about the idea of discarding false faces in favor of real ones when confronted with conflict. Masks can help protect us from being wounded, but in the larger picture, embracing our true faces can perhaps offer even greater gains.