Magilumiere benefitted enormously from having a little room to breath. It started with great art but a seemingly rote story. Turns out a lot of the first act was a subtle foundation for the second. Now 80 chapters in it‘s spooling up to tell a similar but much richer story.
The twintails are a great example. They’re a surface level magical girl trope, indulgently played straight in this chapter as fanservice. I assumed Sakuragi had them because magical girl protagonists have twin tails. While that’s true, they’re also a symbol of her innocence and idealism, initially in plain view but now hidden, tempered by the realities of corporate society and harsh circumstance. Innocence and idealism are themselves a hallmark of the genre, so that’s a trope representing another trope. Pretty clever.
This manga worked as a well drawn modern magical girl manga played straight. With the corporate element it was also an okay deconstruction of the genre. Now based on its current direction maybe it will be a critique on the cynicism of other modern deconstructions of the genre. This chapter is a big step up and raised the bar of what I expect from the rest of the manga. Really enjoyed it.
I think you've hit the nail on the head, especially the bit about her twintails. While a lot of manga will have characters change their hairstyles to reflect their new maturity or just the passage of time, this is the first time it's really struck me as a true sign of maturity beyond the "symbolic" sense. Honestly, even before this chapter the short hair felt more symbolic and kind of odd. When she started issuing orders in this chapter before transforming though, she honestly felt so much more like a professional businesswoman and "presidential" with the short hair. It really does give her an air of maturity.
Seeing the twintails return as part of her transformation shows she's still the same Sakuragi we all know though. Like you said, they're symbolic of her innocence and idealism. The dichotomy you described is actually even more fitting for a magical girl: they usually hide their magical girl activities behind a normal facade, and that's exactly what she's doing. Acting like a corporate businesswoman in her daily life, but embracing her true nature when she transforms.
This series definitely had a slow start, but it's done well to continue raising the stakes and build up the world. A lot of manga don't take that time to build things up and try to jump from one action sequence to the next. This one does a good job with the overall pacing.