Ever "browsed" thru a fileserver to doubleclick the document from Finder/Explorer?
Bad for you, if that file is in use by someone else, because:
Now you can redo the browsing within InDesign, just to access the "open as copy" within the file-open-dialog.

What if the "No access, maybe locked."-warning can be a dialog like this: "No access, maybe locked. Try to open as Copy?"

...at least for macOS. Virtually all macOS apps, especially those developed by Apple, support Emacs-style key binding that are incredibly useful for text navigation and text selection purposes. As an almost daily use of InDesign—and a 26-year employee of Adobe—I would very much like to see this supported. Most of the commands involve the use of the "control" key, which appears to be unused for InDesign keyboard shortcuts, so this is likely to be a no-brainer.

Let user customize toolbar with ability to remove less frequently used tools or rearrange order of tools. Maybe under preferences?

A preview checkbox in the grids panel under document preferences. So that you can make changes to the document grid or baseline grid without having to close the preferences panel in order to see the effects your changes have made.

Under Preferences > Units & Increments, the Keyboard Increments preferences should be application wide, not document specific.

People share documents and templates and have their own way of working. They expect keyboard shortcuts to work consistently. It is unintuitive if in one file point size and leading change in two point increments and in another they change in one point increments. There is no reason for these preferences to be document specific rather than application specific.

When I'm doing a find/change in a "Auswahl" (in english maybe "selection"? – screenshot A), the "Search" area is always changing thereafter automatically to "Textabschnitt" (text section? - screenshot B).
It would be great if there would be no change.

When copying asset(s) to the desktop you always have to search on wich pages you copied that asset(s). When all pages are on the same desktop, the copied assets are more easy to find, because they are always on one desktop.

Hi, might just be me, but the little squares to denote in which layer an object is in is too small, or not very co-operative.
If I need to move something from one layer to another, I find it really difficult to hit the target right to move the item, the square is too small.

I am not blind, its just the one element of the UI that I constantly don't get a positive result from first time, normally takes 3 attempts!

We work in a bilingual environment, and constantly need to switch between French and English.

Pretty self explanatory. It's very useful for example if you need a marquee or an odd shape to serve you as a guide and most importantly, the snapping in InDesign between a line and a guide is so different and so hard to snap to a path.

Ability to sort fonts by install date, so the most recent ones are shown first.

An Actions Panel that runs the same type of Recording/Playing features as Photoshop and Illustrator already have would be fantastic.

I keep my panels on the right and would like them to expand to the left and collapse to the right. This option is definitely available in Adobe Illustrator. Seems like a logical feature and probably easy to implement.

Back in the day you could click on "Help" and search for everything and this feature would help you right away. I can't find it now and hope you will bring it back. It's the fastest way to help yourself. Please bring it back. The feature is also to be found in Photoshop.

The GUI for Index item/topic management is painful to use. For instance, looking for an item means constantly having to scroll and expand/collapse items in the topic list, mainly because it is so small and secondly because it auto-collapses all the time. This UI should be in a resizable panel, a search field could quickly narrow choices.

Scrubby zoom option in the Preferences with enable/disable toggle, just like in Photoshop and Illustrator.
And the default option should be unticked (disabled).

This should be a setting you can choose when relinking each image. One image might need one option and another image might need the other - not just a blanket pref setting per document.