As you can see multiple elements are not aligned correctly in the picture above:

• The " Include error message in the return body" is lower than it's label
• I don't see any extra added information in "Error Response Codes The return code to set according to different error situations", as the table header does a great job of describing what the form is used to do.
• The dropdowns and error types aren't centered
• I'd make the error kinds bold, to help navigate users attention through the form
• It could be beneficial to match the HTTP response code color to the colors used in apicurio editor

notify: aglass-1 this looks partly as a UX issue to me, so you can look at it as well (please let me know if there's a better way how to notify you )