You make really good points about natural language evolution, and we can see how some of that has worked in English, where a desire to de-emphasize gender in job and position titles has sometimes produced natural-(ish) results that overrode what people were trying to manufacture.

Look at titles for politicians, like city council person or Congressperson. They caught on to some extent and you'll find them in dictionaries. But they can grate on people's ears even though we're often loathe to say councilman or congressman, especially when the person in question is a woman.

So instead, we started to say things like council member, or representative, or member of Congress. Those expressions follow more normal English usage patterns, and people tend to experience them as ordinary.

When the waiter/waitress distinction started to feel unnecessarily gendered, somebody tried to manufacture the word waitron. Not surprisingly, it never caught on. People just started saying server, which feels completely ordinary and in line with common English language usage.

Stewards and stewardesses on airplanes became flight attendants, which is a little more of a stretch and more clearly manufactured, but people have accepted it, probably because it's an ordinary expression that follows ordinary English expression customs.

Obviously, we've had a bit of an easier road to hoe because our language isn't as gendered as romance languages are, and let's not even get into the great "Latinx" debate, other than to mention that as an English word (not a Spanish one), it really doesn't work according to internalized English language customs. My guess is that it won't catch on for that reason.

I could say the same for certain proposed neo pronouns that don't
seem to fit with typical English-language phonology or morphology.

But, languages are remarkably adaptive, and when needs for words exist, it seems like words catch on fast and spread like wildfire, often all on their own.

I expect that whatever languages we're speaking, the need for gender-neutral words will produce gender-neutral words, maybe just not the ones we're expecting or trying to create.