Some insight as someone who knows JPN:
I'm not so sure as "yaru" or やる as the term. For one, it's a very general and versatile verb that means "to do" for a lot of different contexts, I feel like we should stay away from る ending in general cause it implicates verb, and it's just such a common verb at that. It feels like proposing the word "is" or "go" as a new term. (Another, it can have some negative or vulgar connotations like a euphemism for SA.)
Moreover, though they originated in Japan, the terms yaoi やおい or yuri 百合 are not used much as their counterparts BL or GL. (Which HL is for hetero, otherwise NL meaning normal love, but HL is being advocated over NL because of the connotation. NBL or XL might be potential nonbinary term, based on X-gender which is Japanese term for nonbinary or agender.)
Though in the West, particularly in fandom discussion, we've adopted yaoi & yuri as more common terms, so it makes sense we want a NB variant.
So what do I propose instead?
One common term I've seen floating around is simply "yaori" which combines the two terms, yaoi and yuri, so it's pretty easily communicable.
If I wanted to coin a term instead, my throughline of thought would be that it has to start with yo よ.
In Japanese, the ya や line of characters is ya や, yu ゆ, yo よ. We have yaoi begins with ya, we have yuri begins with yu. Thus it follows the new coined term could begin with yo.
I think a beautiful term could begin with kanji yo 夜 meaning "night."
Meaning "group of the night." As in, nonbinary is like the night, elusive and hidden.
It's possible to substitute the ha kanji 派 for other kanji with the same pronunciation to create a different meaning. Like 花 flower, 葉 leaf, 歯 teeth. I think 夜花 for "night flower" would be really pretty and cool.
I personally like this pronunciation/set of syllables the most.
Something to consider is it can probably also be pronounced as yowa よわ meaning "scary." This can be a good, neutral, or bad thing.
From 夜明け (yoake) meaning "dawn," but shortened.
Literally, the characters together mean "night" and "brightness." It can symbolize the night and the day meeting each other. Perhaps nonbinary love is like the space where day and night meet. It's not quite the moon or the sun, not quite night and day, but something in between those things.
I personally like this meaning the most.
In the case of yoa よあ, there's a possibility to append other kanji or syllables at the end making the term longer and different from yaoi & yuri, to emphasize the unexpected difference. (Also, this would mean it has the same amount of syllables/characters as yaoi.) For example, we could go with yoake 夜明け which just means dawn straight-up.
There's a lot more potential terms or readings we can try to workshop, but those are my strongest contenders. And besides, the よ requirement isn't totally strict, it's just my personal idea to do so. Terms starting with ya or yu could also be workshopped or proposed. Just depends on what meaning you can make from it. Hell, maybe it doesn't have to start with the ya や line at all.
Coining a term for "nonbinary yaoi/yuri" is difficult because we are trying to create a Western term adopted from Japanese etymology and queer fiction subculture. And NB love isn't necessarily a "genre" as much as yaoi/BL or yuri/GL is, unfortunately. And with how BL/GL terms are favored in Japan right now, it's highly unlikely we'll see the invention of a yaoi/yuri counterpart term coming directly from Japan. As aforementioned, that term would most likely be XL or NBL, not a term that matches closely with yaoi/yuri.
Right now, I still do see yaori as the best, most easily communicable term as a result of it evolving naturally out of yaoi & yuri, but I do agree it would be nice to have some term specific to NB at some point.
