I'm quite pleased with how I've set this up and it wasn't the first time I developed such a feature. So far I have only needed two variables for verb conjugations and doesn't look too bad when writing, for example:
paragraph("{heshe} walk{s} to the beach.")
paragraph("{hisher} favorite hat is on.")
paragraph("{heshe} {is} ready to party!")
My paragraph method adds the text element to the main view but not before using a dictionary to insert the variables. For example, in the they/them preset s has an empty string instead of an "s" and is becomes "are". Now that I think about it though I may need a es variable for verbs like goes/go.
Anyways! Just wanted to share a neat little thing. I think it's pretty easy, and I should be able to extend this to neopronouns the player can type in. Also I have been writing everything in 2nd person perspective and I wonder if it would be at all better to write in 1st person perspective. The added benefit is an opportunity to assume more personality and internal dialogue for the player character but at the cost of losing the internal dialogue of other characters which may not ever need to be present in the game anyways. I'll stick with 2nd person for now, it's more in line with how most other text-based games play.