Preprocessor : keyword charset incorrectly seen as empty

[Siorki]

Upon running RegPack on js1024.fun 2013 entry Lucky The Rad Dragon, preprocessor output features the following block

----------- Renaming variables to optimize RegExp blocks --------
All variables : EFGMabcdefghijklmnopqrstuv
in keywords only : (none)
in variables only : FGfgjqs

Obviously the empty charset from the keywords is wrong, as there are methods like remove or append in the code.
Is it merely a cosmetic issue, or does it impact the result of the preprocessor ?