I mean, but they being used a singular has been a thing outside of people using different pronouns and this issue being pronounced (lol). You can also refer to multiple people and so can the Dutch formal equivalent of "u".

There's lots of instances of things in language cussing slight confused, but they're usually not hard to overcome.

Maybe say "they went with that group". Or just the person's name. If I don't know the person, I might make a little description of them, like "oh yeah, the cool person we just met with blue hair".

Pronouns and generally gendered or gender neutral language like that is a little bit confusing in Dutch (outside the 'traditional' binary genders). It all works a lot nicer in English, but maybe that's because I'm more familiar with everything in English and I speak it more. But in Dutch I'll generally rephrase altogether and avoid it.

I'm sometimes confused how to fit neopronouns into my grammer. But honestly just doing it and fixing it when messing up seems to work okay. I do like neopronouns. All words are made up, why not make your own?