Yes sure i will add more example with all of its features (in the GIF) and more examples where GNU diff tool does not work.
Yes, it does work if you shuffle lines. There is a --primary-key option that lets you choose what columns uniquely identify a row, it can be compound too. Its assumed to be the first column by default.
It's a great idea. But since it's actually not tail at all, but rather a very specific text filter that looks for date strings and translate them (assuming it would work, say, on a file with two timestamps to a line), maybe another name would be better?
I guess this is more "tr for timezones"? So maybe tztr? (time zone translator)?