Interesting thread.
That said, where OP has a very good point about being careful about this when writing modern Chinese characters -- please keep in mind that this is relevant to China-Chinese and not to the millions of diaspora around the world. https://twitter.com/crownsnbirds/status/1311436002087460864

Courtesy names aren't really a thing in Taiwan either, for Reasons, but there is room for it, in a way.
There is a section on the passport for "alias", frex.
My brother's passport has his Chinese name as the proper name, and alias his English name.
My "alias" is my former name.

There would theoretically be no reason at all for me not to choose to give up the practical option of using my former name as an alias and instead choose a courtesy name.

I have mentioned before that my family went through a couple of name-change waves?

Some of them, like my father, had a name change, but never bothered (for reasons) to get it formalized. In this case, it's a sort of courtesy name situation. Ish.

And y'all have heard the arguments that screen names and handles are essentially the modern version of 號.

Which is just to say, that if you want to call your characters a million different things, there's precedent and ways of doing so.

In blog post the OP linked, the writer concludes with "courtesy names can be a thing again, but be aware that if you introduce yourself as x, also called y, also called z, most of us are just gonna side-eye you", and yes?
This is legit?
But also like 80% of us are drama queens?

TBH, and I'm sorry if I'm stepping on anyone's toes here, but saying "I'm Katje, also called Kyr, and some know me as Kyraninse" is ...not necessarily more pretentious or annoying than "Donald 'Grinch' McDuck, call sign Gold, known in the motorcycle club as Tightass".