This happened to me when trying to translate [[Padma Purana]] and [[Kuching]] from English to Czech, and probably happens in other articles, too.

Click on the first paragraph. Click on any of the lines in the translation paragraph. Press the End key. In any line except the last, it puts the caret at the end of the line, as expected.

On the last line of the paragraphs, the behavior is different:

• In Firefox, the browser scrolls the whole page to the end.
• In Chrome, the caret goes to the beginning of the line instead of going to the end.

Both behaviors might be upstream bugs ;)

This might also be related to T104811.