I'm pleased to report that I have tested a ROM that I had not tried before and have confirmed that it meets all of my requirements.
The Nazim's crDroid GSI is the best ROM for the Legion Y700 (I didn't like the logo, so I didn't use it until now).
Below is a list of the outstanding features of this ROM.
・It doesn't have a fixed lock screen in portrait orientation like Corvus or Descendant.
・It doesn't contain superfluous and undeletable files like "su" like Lineage.
・It includes face unlock unlike ArrowOS (by the way, crDroid and ArrowOS are built by the same person, I wonder why he didn't include face unlock in the latter).
・It doesn't cause any noticeable glitches like ProtonAOSP or Pixel Experience (it still runs the Alpha version of the
Lawnchair Magisk Module without crashing).
・This ROM is so customizable that you don't even need the Magisk or LSPosed module that you have been using. The status bar can be customized, and even the volume step can be adjusted.
・The default wallpaper of this ROM is very beautiful (my personal opinion

).
・It can pass SafetyNet. most other 12L GSIs could not do this.
Of course, this ROM alone is still not enough in some areas, but I think that can be improved with the App placed by Mr.
@NisseGurra and the modules in
this link
(Click the "Magiskモジュールのダウンロード" button to jump to Google Drive and download it). This module enables automatic brightness change of the screen, and also allows assignment to the right switch (originally the game mode activation switch) using the Button Mapper.
I hope all Y700 users will use this ROM. Thank you.