don't overthink it. You've clearly gone for a light-hearted, carefree guideline, suitable for a simple, short game.
It's OK to go for a 'show, don't tell' design: think more FOBS / Milky Quest (and less Chrono Trigger). Names (Y, R, G, B...) are already a big hint, you don't have to write 10 000 lines of story to make sense.
The player WILL find sense if he/she doesn't get bored BFing. Don't have a plot line? Just include some hints at the very end, and you're good. Struggling with the difficulty curve or RPG progression? Screw it, fok balancing, FOBS/MQ have neither, and you don't need 'em since no fight gets too easy or too hard that way - proven by the demo.
That's coming from someone convinced by the BF mechanics, and the initial feel SexMachine gives, but: more of the same is good enough IMHO.
I willingly oversimplify, but:
I'm pretty proud of the general system we made. I feel like it's rewarding to understand how the girls move, while dealing with the enemies skills.
I think I did a relatively good job with the enemy AI as well.
Other quotes (un-exhaustive & chrono-logical):
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Game looks fantastic
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Really unique battle system I haven't seen before. [+truckload of sensible comments]
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This game looks really good
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Game looks great, and the battle system is super neat
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looks very promising!
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I have to say, I'm rather impressed!
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I can confirm all of the above
-> You have all rights and reasons to feel confident, and much to capitalize on.
This was designed as a short game as an improvised collab. Keep it simple - Milky Quest style.
Simple, practical and realistic, are words which built empires. Over-ambition, one that'd destroy them - including in the egg. Procrastinating before a gold mine doesn't get the gold out (speaking from personal experience).
It'd be a bit silly to be stuck in a rut, when all that would reasonably suffice is 4-5 maps exactly like the Demo one, with no real desideratum for other mechanics (they'd be a cherry on top, at best, and most of us would rather pop them anyway).
The existing system is already sufficiently complicated, and not overly so; consider dismissing entirely whatever is eating up your development time (and courage). Your ideas ain't wasted, since you can always do another game afterward - a sequel, even (PureDreamCreate as proof, to keep it robotic).