Creating a poly fill on tNames doesn't seem to work for what you want it to do (it seems to create a solid fill not a pour).
You will also run into issues with the fact that not all "silkscreen" information is on the tNames layer, some is on tValues or tPlace and sometimes also tDocu (for badly made parts).
If you are getting poor quality results from the silkscreen, I don't think adding a poly fill will help anyway. Try making the font size or proportion bigger instead, or post a photo of what doesn't look good.