Light Novels should no longer be divided into arbitrary "parts" but use the actual chapters
Books have natural divisions and breaks called chapters. When I want to pick up where I left off its easier to remember which chapter I was in, or when referring back to a wiki, everything is always divided into chapters. I shouldn't have to go into the reader and look around to find the chapter I'm looking for.
If the chapters are too big for translation chunks, you can divide them in half (Ch. 3 pt 1 and Ch.3 pt. 2) or change the release schedule to fit. Chapters provide a more natural stopping point rather than these arbitrary chunks. They feel completely arbitrary and useless, as they are a division that only jnovel club uses.
At the very least, change the organization of completed volumes from parts to chapters. You don't need them anymore right, because the translation is done?
The parts are only used for the weekly publishing schedule on the site. Published volumes are not divided in parts but in their proper chapters already. But that work is done only for the epub files, even all typos/errors reported are only fixed there once a volume is published. They never go back and fix up the parts on the site. (They only keep the parts around for the monthly catchup.)
Basically you want them to change the name from part i to chap i1 part i2.
It doesn't seem that usefull as you can just look what chapter was in the last part, having a number of parts which number are continue has his advantages, mainly if you've read part 1 you know the next is part 2, whereas in your system chapt 1 could be follow by chap 4 if chap 2 and 3 are short.
Also having a regular shedule is a good think as people know exactly when they can come and read the new part (most of the time) without having to check the scheddule every time, plus you can create habit, for exemple personaly i know that i had to keep some time around saturday 16h to read Grimgar, and it became an habit to take a break around that time to come and read.
Where i could agree with you, is that chapter are the natural place to cut, however most of the time it seem like the parts end at the end of a chapter or at a break in a chapter, it doesn’t feel chose at random (most of the time).
Also it seem like your mistaken, parts are only for prepub, they don't appear in the ebook.
What would be your solution to Der Werwolf, which has no chapter divisions? I think the system as it is is fine. Prepubs don't last very long anyways (2-3 months at the most), with the exception of catch-ups, so it's not that big of a deal.