According to the consultant, and this was a long time ago, they ruled out Carpel Tunnel and other causes, but there were clear indicators of damage.
At it's worst, if the main three fingers of my R hand touched, just touched, any surface it was painful. It really was RSI as back then I was mouse clicking many many thousands of times a day.
What fixed it for me, apart from slowing down, was to start using a Wacom pen/tablet. Even so, by a Thursday my hand / fingers hurt and I used a splint when not working.
I have read more about TMS since I read your post and while it could fit I do not believe it does. In part because of the very localised pain, and in part because ... it's hard and privacy destroying to articulate but no, it doesn't fit.
As for the daith. It worked for me. It has worked for my daughters. It has worked for a friend and also for a random delivery guy who looked rough one day, I suggested it and he came back a few days later to say he no longer has to chew codeine all day.
If something works for someone, great. But I don't go with generalising.