Honestly, leaning into the idea of "who is, and what makes them, the original" is where I was hoping this would go. Sunao despairing over her own personality and how she's changed from "Nao-chan" to "Aisawa-san" feels like it could be attributed to Nao's appearance. The more Sunao ...well, pushed all the hard & difficult parts of growing up onto her replica, the more she stifled her own chances to grow alongside her classmates.
I suspect that's what happened, at any rate. If Sunao was as bright and cheery as Nao, then relying on Nao more and more left Sunao cooped up at home, avoiding everything and everyone, and stewing in the resentment of watching her duplicate continue to flourish. We know she took it out on Nao constantly as well...and it's only been recently that they've started making up and Nao has been allowed to simply exist and be herself (albeit only when she can be physically separate from Sunao, for obvious reasons).
But I hope that Sunao discovers that she's allowed to be, and doesn't have to accommodate or apologize to anyone. She has "growing up" to catch up on, but it's not too late. All the more so when she has a core group of friends--not to mention Nao herself--who care deeply for her, and would support her at the drop of a hat.
The metaphor of being afraid of being authentic to yourself and what "version" of you must be presented to the world is lovely and deep, though. There's a lot of fluffy moments and cute bits with the romance between Aki & Nao, but that underlying aspect of what it means to be able to create another version of yourself reamins. And finding out that more and more of the cast have--or, alarmingly, had--duplicates of their own is expanding the world (literally, I guess), and growing the chance to hit on that more existential side of the narrative.
Thanks for the TL. Glad I gave this series a chance, because I've been enjoying it immensely since it was restarted.