I was with my previous girlfriend for ~5 years, and have basically been using Gboard the entire time. We communicated via various messaging services literally every single day. If I was to try swipe-type her name right now, there is a 50% chance that it will suggest a different but similar name that I think I have literally never accepted as a suggestion.

I was expecting this feature when I got my first Android phone over a decade ago, and I am still waiting for it. Is there some engineering step that I'm missing? Model my typing history and use that for prediction weightings. Is this unfeasible on my phone hardware?

Google's Android keyboard (GBoard) has swiping capability. Still not great, I think the problem is the keyboard isn't able to go back and correct previously typed words based on subsequent contextual information.