The last step in the production process of flatwounds is usually polishing.
Halfrounds are ground down - D'Addario Half-Rounds are run through Zero Grinders and then packaged. They do not polish them after the grinding process as it is already hard enough to clean the lubricant from the strings in the grinding process.
Dean Markley had "Fret Masters" which are now discontinued strings... They were "Polished" over the fret area to achieve less finger noise.
D'Addario does currently have a guitar string set that is polished, but no bass set like that.
The new Steve Harris Rotosound flats are now ground and polished more than the other Rotosound Jazz Bass flats.
I have heard of users polishing their own half-rounds... You can always try... If it doesn't work, you may just be left with dead polished strings