The bug
As of 1.13❓ , Minecraft can now detect international keyboard layouts and change the display names of keys in the Key Binds menu accordingly. However, this is not the case for the two Alt keys, which are named according to the US layout at all times, which is inconsistent.
How to reproduce
Have your keyboard settings configured to a non-US layout, e.g. UK
Bind controls to the "Alt" key and "Alt Gr" key
Observe
Expected results
The control bound to Alt would say "Alt" and the control bound to Alt Gr would say "Alt Gr" (or "Alt Graph").
Actual results
The control bound to "Alt" says "Left Alt" and the control bound to Alt Gr says "Right Alt". This should only happen for US keyboards and other layouts without Alt Gr.
The new bug tracker layout makes it impossible for me to see who closed this and why, but given the recent fixing of MC-121375 and MC-189953 this seems like something worth bringing attention to again.