So I noticed the ipatch is KINDA working (unless it's just the way the relationships are set up).
The MC does refer to Tara as whatever relationship you set up for her at the beginning of the game, so that works, at least during narration dialogue. The problem is the MC and other characters refer to each other as whatever name you set for them, which is the killer.
My suggestion for the dev (or anyone who creates a patch) would be to set the UI and script up like so:
Name: Janice
MC Relationship: Mom
Janice Relationship: Son
MC refers to her as: Mom
Janice refers to MC as: <whatever>
This is how a lot of games handle it so some characters to a character as one thing, and others, another. I thought about poking around and checking it out, but I couldn't find where the script files were pulling the names from. If someone can point me in the right spot, I might take a look.