Thank you for your report!

We are currently working on keyboard layouts for KeyEvents. 

Most text input is going through the IME code path, which takes care of keyboard layouts, IME display, etc. However for raw KeyEvents we still need to do more work in terms of keyboard layouts. 

There are two steps to this. The first step is mapping the key codes as described in https://developer.android.com/reference/android/view/KeyEvent.html

But those key codes only know US keyboard keys, there are no umlaut or other special character codes, so this will account for things like switched y and z keys, etc). 

Special characters need another layout map called KeyCharacterMap, which maps the key codes into unicode characters.

The key code mapping is currently targeted at version M54 and that will match the behavior you are seeing with ARC Welder. 
The KeyCharacterMap to provide full unicode support is going to be a more complex issue and will probably not get in before M55. 

https://developer.android.com/reference/android/widget/TextView.OnEditorActionListener.html
In our App we are using this interface to read enter key from keyboard or barcode scanners.
mEditText.setOnEditorActionListener(new OnEditorActionListener()
{
    @Override
    public boolean onEditorAction(TextView v, int actionId, KeyEvent event){
    if (event.getKeyCode() == KeyEvent.KEYCODE_ENTER){
        // some app logic
        return true;
    }
    return false;
    }
});

It's never get this callback.
Tested on Windows 10 and MAC OS X with latest ARC and chrome canary.

#3: That seems to be a separate issue of the one being discussed here, but to clarify: Are you using this ARC: https://developer.chrome.com/apps/getstarted_arc
or are you using the native Android with the Google Play Store running on Chrome OS? 

Yeah I am using this: https://developer.chrome.com/apps/getstarted_arc
on MAC OS and windows 10, have not tried on ChromeBook or Chrome OS.

https://developer.android.com/training/keyboard-input/style.html

omprakashsrv@gmail.com: That is a separate issue on a separate technology. I have filed a separate bug for this: https://bugs.chromium.org/p/chromium/issues/detail?id=637293

Same issue. Acer Chromebook 14, Chrome 61

Termux on a Chromebook with German keyboard is receiving keys from US layout. Sounds like this issue? (63.0.3239.86)

There is an internal bug tracking the issue at b/27877642

It looks like yhanada recently made some changes to fix the issue. I will re-assign to him. 

The first step mentioned in comment 1 should be fixed already.