each of us can wear one half of the heart

I'm gonna be a bit of a Debbie Downer for a second and point out that it's not just people who use screen readers who have difficulty with those fonts. It's also people with dyslexia, lower reading comprehension, lack of familiarity with cursive or fancy fonts, and non-native speakers.

I myself am none of the above, but I still can't read more than one or two words of either strikethrough or Zalgo text before I can feel a strain in my eyes.

For those who are able to visually read the words, I'll explain what the issue is with screen readers. Fancy Unicode Text isn't actually text. It's letters formed by unicode symbols that were created for use in, for example, mathematical equations. Each of those symbols has a name, and a screen reader will read out each "letter"'s name instead of reading the whole word. I'll put an example below, as an image, to save people who are using screen readers to read this post (there's a brief alt text though).

example courtesy of https://givemefonts.com/blog/accessibility-in-unicode

So, now that everyone is up to speed on the question, I have one question and two possible solutions.

The question: What is the purpose of using the fancy unicode text?

First possible solution: If you just want to be able to differentiate the font and/or colour of text within a fic, you can do that with a work skin and leave the text fully readable by screen readers. Here's one that was created for Undertale and has a whole bunch of web safe fonts you can switch between. There's one for Homestuck as well. And a third workskin that does lots of formatting, including fonts and colours.

Second possible solution: If you're going for a specific look that can only be achieved by fancy unicode text, then you might want to include that as an image and set the image's alt text to be the plain text version.

In most cases cases the snarl of glitch text or long strings of unicode-symbol-names-being-read-aloud is an automatic 'hell no'. Basically either is right up there with overly long ASCII/emoticon dividers in terms of annoyance factor. Also, a lot of the look of unicode-symbols-as-text can be more-or-less replicated by font and style changes such as using bold and italic or a cursive font, which are at least TTS friendly even if not always particularly great for people who sight-read with vision/perception issues. Though I would hope people with those issues are at least using software that ignores document CSS and forces the use of friendly-to-them fonts and formatting (the software I use has such features in addition to TTS, you just have to have enough sight to go through the menus changing things to your particular satisfaction).

So I highly second just using Cool Regular Text instead of unicode text, with maybe an optional skin if you want to be particularly spiffy about it (though note that skins get thrown away when the fic is downloaded, so I and my ereader likely wouldn't even notice any difference... unless the lack of skin causes a bunch of stuff to break in creative ways). So yes, look at the skins linked in the above reply, if you're really ambitious maybe even hit up the W3 Schools site and learn some CSS for ways of affecting text appearance yourself.

Yes, it's literally nonsense text - it's like that post about book titles that use random other-language characters 'for stylistic purposes' just because they resemble ISO roman alphabet characters, and how howlingly funny that reads to people who know what that character is actually pronounced like.

It gets even worse if you're using a lot of foreign language letters, because some TTS is smart enough that if it notices several same-foreign-language letters in a row, it will switch to that language and read them that way. Yes, the TTS my software uses is smart enough that it does this. Yes, it's very funny (and very immersion breaking) when my ereader suddenly switches to the (usually female) default voice for a random language, says something in that language, then switches back to my standard voice settings (male UK... sounds very Masterpiece Theatre) and continues on smoothly in English.