Hello!
If the inserter is connected to the logical network, then this is how the window is displayed (the "filter helper" mod is also installed).
Maybe it is possible to change the position of the window? Something like with the if filter - if the logical network window is enabled, then stick the inserter window below, or something like that. Or maybe there is some kind of check whether the inserter is connected to the logical network or not.

And is it possible to place the top of the window in the center? The bottom (offset) is always in the center, and the top is always on the left, not harmonious :)

Centering the top one should not be too hard; I planet to do that in the past but for some reason never finished that.

Regarding the first one, from my understanding I can only add UI's on specific locations, if anotehr mod add ui/s before or after mine the position will be shifter by the game.

My only control is "player.gui.relative" and inside this there's a list of elements, the order with various mods add stuff here changes the result, I can't control that order so from what I know it's not possibiel to move the UI to another location.

Heh, while I was looking for at least some useful information, I came across this post - https://www.reddit.com/r/factorio/comments/14yli3t/trying_to_revamp_bobs_inserters_with_a_coesive_ui/#lightbox
An interesting idea, he placed the inserter settings inside the inserter interface window :) This is of course the ideal option, if you take the current inserter settings window and place it in the inserter interface, there is just enough space there :))))

Unfortunately, I did not find anything useful, although it seems that these settings are somewhere, but I could not find them in the game files. In general, the inserter has logistic and logical network windows opening downwards, one after the other. I assume that this logic is specified somewhere, like if "parent" = logical network interface, then anchor = defines.relative_gui_position.bottom, otherwise defines.relative_gui_position.right, or something like that.

I'm not good at this, I would like to help somehow, but alas...

Okay, so I read that post, I will try to do something with the "anchor" parameter, but I doubt I can bypass the circuit UI.

BTW, I centered the main selector GUI for the next release.

Hi!
I came across this line in one of the mods:
enable_logistic_control_behavior = false.

It seems that this is the logistics window that you can try to bind to, like if it's active, then the anchor is below, if it's not active, then the anchor is on the right, or something like that.
I don't have the same coding skills as you, so I can't even try this :(

There is also an article on the site, maybe it can help somehow :)
https://lua-api.factorio.com/latest/classes/LuaInserterControlBehavior.html

enable_logistic_control_behavior controls if the inserter is allowed to connect to the logistics network or not https://forums.factorio.com/116579.