For the login.html page there is a file you can create in the theme folder (if not already available)
> Root of the project > theme > js > login_i18n.js
It will be auto generated at that same location in your deployment folder at
> Root of the project > deployment > web > login_i18n.js
Hope this helps.
You mention 'for fail AD login'. This indicates that you are using a module/extension for the login page, is that correct? Because the default login texts are managed in the system texts, but if you have a different login page, you should be looking for this in that module, I believe. Maybe you can mention which module you use for the AD login? So I can look into it further.