that layer of lacquer is actually a UV coating
while polishing them like that will make them look good again, it will be short lived.
you really just need to sand all the old stuff down and take it to about an 800-1000 grit and then clear them with a UV clear paint like this stuff.
2K Clear coat - SprayMax
its a 2 part epoxy with a high UV protection
I did mine about 3 yrs ago and still look like new