Turns out that the endnote character IS in the hidden characters chart… there’s an updated one that includes it:
https://creativepro.com/updated-guide-to-indesigns-special-characters.php

Unfortunately, Publish Online is not responsive at this time. It is only designed to recreate your InDesign pages.

There are some other tools for getting HTML out of InDesign, such as in5. You can use InDesign’s liquid layout features with in5, so it’s semi-responsive, but it’s not really the same thing.
https://ajarproductions.com/in5course/?lesson=flexlayouts

Andy, names are tricky… GREP can only find very clear patterns. It doesn’t know about things like “names.” For example, the word “Cook” could, of course, be a name or a word. So GREP probably can’t tell what a name is.

Dakota: No, if you made the pages with a photo/pixel-editing tool such as pixelmaster then InDesign can’t go in and change those colors (other than do do a global change from RGB to CMYK). InDesign is a tool for laying out pages (text and graphics), not editing photos.

Well, unfortunately, there is simply no way to maintain the vibrance of rich, saturated colors of many RGB images when you convert to CMYK with a 240% ink limit. It’s like trying to maintain incredible dynamic range on an old beat up audio cassette. (Does anyone remember cassettes anymore?)

This is one reason why many color books are printed on offset or digital presses that can handle 300 or even 320% ink. You can get bright colors from 240%, but only when they’re relatively simple. For example 100% cyan and 60% yellow is only 160%, but it’s a nice bright green.

I wonder if much of the problem for your graphic novel is in the dark colors, like black. And I wonder if it might be better to convert the images to CMYK in Photoshop first. I usually don’t recommend converting in Photoshop first (I believe in placing RGB images into InDesign) but this might be a case where you’d want to. Hm.