First off, thank you for implementing "Autocomplete in the the table". It's very helpful when copy and pasting the same names over and over.
The downfall is sometimes the autocomplete makes suggests that are not helpful. For example,
  1. For my polygons I'm trying to setup the country as "CA" abbreviated from Canada.
  2. At one point I had a point for an amenity where I made the country "Canada" but then deleted it.
Now every time I try to type in "CA" it tries to make it "Canada" I'm fighting just to copy and paste.
My suggest would be to teach the auto-complete what is correct. If the auto-complete pops up "Canada" have an "X" beside each suggestion. If that suggestion is incorrect I can hit the "X" and it prevents it from suggesting for what I'm pasting.
And then it turns back on when I start a new word.