Steps to reproduce:
1. Prepare a question of type "Embedded answers" containing some SHORTANSWER and NUMERICAL subquestions
2. Put the question into a quiz, log in as student and attempt the quiz
3. Into the input fields, put a text containing some HTML code (tested with <b>two</b> and <i>2</i>)
4. Submit the attempt, log in as a teacher and review the attempt
In the table "History of responses", the teacher shoudl see exactly what the student typed, that is "<b>two</b>" and "<i>2</i>"
What actually happens:
html_to_text() is used and the teacher sees "TWO" and "2"
To be consistent with the plain shortanswer qtype, format_answer() should use plain s() without html_to_text() for oneline input fields