OK, OK, I know what you're thinking: "Why can't we just let people use some fancy pronouns and move on already?" and I agree. I don't have anything against people using this feature and I do find this topic a bit boring at times. I am here just to point out some flaws I don't hear anyone talking about and offer some solutions. (but I don't really look for this kind of discussion, so it might be well known problem, in this case feel free to go read something more exciting...)
Imagine this situation: New US president was elected. Biden died of old age and Trump was not popular enough so someone new got this position. This person goes by ze/zir. US elections are already important for rest of the world by themselves, not to mention this would be the first president (to my knowlage) that uses alternative pronouns. This information will be presented by news all around the world and you don't want to misgender zir. (am I using it correctly?) I'm genually curious how would this be resolved.
Most languages tend to group words by grammatical gender. That is masculine (he) feminine (she) and neuter (it). (there are other systems, but they're less common) Some lanuages, like most romance languages for example, don't even have neuter. In english, this evolved to the point when you use masculine and feminine only for people and gender affects only pronouns. In other languages however, other words can fall under masculine/feminine groups and gender of subject also affects rest of the sentence.
Pronouns also tend to have more declensions than in english. (and they like to be irregular as well) In addition to that, in some languages words like jobs or occupations tend to change with gender of subject, often not having version for neuter and defaulting to masculine form. (at least in languages I'm fammiliar with)
In short, you can't just insert new pronoun into any language and expect it to just work
So how should I reffer to the new president? I could try using neuter, but it may not always be an option and even if it is, it's not suited / doesn't feel natural to use it for people. Thus they/them and not it/it. Few languages have universal they/them alternative to my knowlage.
We can give up and use pronouns based on bioligical gender, but that defeats the entire point. This seems to be about it. I don't have any other fancy possibilities up my sleeve. It seems to be a concept that could only be created in english and can't work outside of it.
So should we ditch alternative pronouns alltogether? Well, I would ditch concept of grammatical gender and multiple pronouns entirely if I could. I just don't feel like it adds anything outside of complexity. Outside of that, if we are going to group people, I don't see problem with them making their own groups as long as language allows it.
I would just recommend to put some fallback standard pronouns in case I can't use kour preffered one. Also if your main/second pronoun is neuter, put (socondary) fallback pronoun for feminine/masculine only languages. You know, not for people not wanting to use your preferred pronouns, but for that one french guy that wants to tell his lithuanian friend about you in fluent hindi.
PS: I might start setting my pronouns to */* or more literal /\w{2,}\/\w{2,}/ (pronouns should contain at least two letters) to see what happens.