+1 for regex checkbox.
My instinct was to recommend just moving to commandline for something like this, but I never new about the bulk rename, and if it exists, it’ll be made more useful by adding regex perl or extended support.
For someone like me that would naturally go to the commandline when things get this complicated, the regex checkbox in the GUI would save me time by letting me see my proposed changes instantly, without having to put debug echos in a script or ls the changes before a mv.