The captions have an option to auto-translate which at least gives you the basic idea. But yeah, and official translation would be nice since there are spots where the auto-captions going through an auto-translate doesn't make much sense at all.
I'm not great at Japanese by any means, but I believe he actually likes the shiny look. The filing of the tips afterwards was to make them not slippery because he plucks the strings with that hand. Slippery nail tips would make picking difficult.
