If luck only affects the % chance of a particular file being dropped, if different files have different drop distribution curves for varying luck levels, and a new file is introduced, that’s going to change all the percentile data we’ve collected so far.

If you find the peak luck value for your target file, that should not change, unless all the distributions are changed after another file is introduced (i.e. ET messes up all the data we’ve collected so far) It follows that, if another file is introduced, though the % drop rate for your target will lower, it will still be the peak drop rate, for that level of luck and forum.