I don't know the name's of 75% of the people I work with (I work with a 100+ people a week) and I really have no time or inclination to make the effort. If someone makes up pronouns that don't correspond to their image they are going to get mad at me because I am pretty much incapable of remembering their name let alone their pronouns. If I remember, cool I will use them but I'm really not going to spend hours practicing. Its not an intentional insult, I want everyone to be happy, I just don't have the effort or inclination in me to expend on it.
The more times I read through your story the less there is to it. Someone introduced themselves, said their pronouns, and you didn’t remember their name. Ok, so what?
Neopronouns are an interesting case, but my previous comment about ‘they’ applies. It’s gender neutral, so use ‘they’ if you forget which more specific pronoun is applicable.
There is another group I am in that has name tags and there are stickers with pronouns I've never even heard of (something like ver/ver, xe,xer, etc.).