Here is a list of items (gathered from Discord) that could be implemented for better user experience.
(not in any particular order)

• The controls menu is too high and not centered

• I suggest shortening Controls mode: to just mode: to prevent text going out of bounds

• The link for the SDL2 Gamepad Tool should be clickable (open in browser)

• The location to put the gamepad mappings should originate from .minecraft (e.g .minecraft/config/x.txt)

• Ability to reload the gamepad DB without restarting the game

• Use arrow-style navigation for menus instead of TAB-style

• Auto select the controller when plugged in, and revert to previous input when the controller is unplugged (a toggle to enable / disable this behavior as well)

• Ability for 'Full Keyboard Gameplay' (e.g camera movement control using Numpad)

• Be able to tap a hotbar slot to select it in Touchscreen mode

Thanks a lot for making this mod! ITS AWESOME!!

• [BUG] The D-Pad Down button takes 2 screenshots instead of 1

Here are some new bugs I found:

• only gamepadtool is clickable in the URL (there should also be a highlight when hovered over to indicate that its a clickable link)
  

• The left and right look bindings are reversed (e.g setting left arrow for look left makes camera look right, etc.)

• Using keyboard look bindings results in mouse-based camera movement not working
  https://streamable.com/bbqo6

Forgot to push, my bad!

I fixed the 3 latest bugs!

i did git pull but it says its already up to date, where are the bugfixes?

The controls menu is too high and not centered

This may not be fixed as it's vanilla behavior for the button list widget, you can see the same thing for the mouse settings for example.

I have an idea regarding that, you could fill in that empty space with a controller graphic like this (example) and when a user presses an input, the graphic will highlight that input.

Sadly, that won't be possible, it's very hard to add (and non-needed I think).

The thing is, the way Minecraft manages the GUI makes impossible to add that, and auto GUI Scale already fill all of the space.

As someone who plays with a GUI Scale 3, there's not enough space for it:

ah, i forgot about the GUI scale

As I added everything and fixed everything (except for the GUI centering which isn't fixable), I'm closing this issue.