The entire thread I pointed you to was about genderless pronouns in use in a narrative dealing with NPC beings in a scifi published game by this company.
I suggest reading that game’s demo, if you have not played the entire game; that will show how one author put into practice the deployment of genderless pronouns for NPC characters.
Good luck with your project — you should design the pronouns to fit your narrative and the only person able to answer what they should be is you. The chart I pointed you to can only help for coding in the proper grammar, whatever the solution you decide on.
Edit: The link to @HarrisPS’s code should also be useful, if you decide you need help deploying the proper scripting in your project.