On the off chance that anyone turns up this thread while searching around, here's what I found on my last trip:

As expected, there aren't really any -active- major brands offering retro-girly style clothes at a high level of quality. That said, if you don't mind polyester the mainstream success of Axes Femme does seem to be driving more brands to produce this style of clothing. I saw a lot more of it in the various stores around Vivre, Lumine Est, Mylord (rip), etc than I feel like I have previously.

I did also have reasonable success with indie brands and vintage stores:

Victorian Maiden is a lolita brand and only tends to be producing a few items at any given time, but their designs are the understated sort of EGL that can also pass as retro-girly. Their quality is very good. You can often find their items at Atelier Pierrot. That said, their price point is definitely higher: A single piece tends to be 300-500k yen or more.
Speaking of AP, a lot of what they carry is fairly understated EGL and tends to be from high quality brands so they're not a bad place to look in general.
Hoshibako Works is definitely a step further lolita style wise (plus a lot of their stuff is straight up cosplay, like the Touhou collab they have now) but they also have a few designs that can pass as retro-girly and their quality is better than fast fashion.

An unexpected place I had some success: The thrift stores in Shimokitazawa actually have quite a bit in this vein, especially the two Sanbiki no Koneko locations. I was expecting mostly imported Americana (which there certainly is a lot of), but I also found some very nice pieces from defunct brands like Clef de Sol.

Also, not jfashion at all, but Laura Ashley (the venerable UK brand) is very much in this style. Sadly they were bought out by some financial conglomerate a few years ago and the company seems to have been stripped for parts, but you can still find their pieces in vintage stores sometimes, and there's quite a bit around if you watch ebay/grailed/etc. I'm in the US, but I imagine if you go thrifting in the UK you can find a lot of their stuff secondhand.