So, I want to make my custom error message "look good" - it seems I'm very limited

related to an earlier question, I plan to use a customized error message - but it seems very restrictive. No rich content editor (like other messages), no images, no tables, etc. I tried creating a General message and hoped I could choose it for the error message...but alas, nope. I have to use a "validation message" which is highly restrictive.

Another solution could be if in a multiple choice question I could show a different error (validation) message for each choice made. It seems that I only get one message per question rather than per choice.

Any help will be appreciated.