I recently put up a PR related to this and was encouraged by TDR to post about it here: Add Control + Shift + Z as an alternate InputChord for Redo by Damon3000s · Pull Request #13890 · EpicGames/UnrealEngine
A lot of popular applications on Windows have adopted Control + Shift + Z as an alternate, or only, keychord for the undo action (Control + Y being the default/standard on Windows). I personally find Control + Shift + Z to be the better shortcut for redo because all the keys are in close proximity so I don’t have to stretch my hand from the left to the middle of the keyboard. Since UI_COMMAND already supports an alternate keychord for actions it was simple to support both. We’ve been running a custom engine with this alternate keychord for roughly a year with no issues.
Side note on this: I was initially confused as to if I should add a mac define block to have the command key used on mac vs control on Windows, but after some digging I discovered that Mac will automatically use Command (and control). It might be best to remove the mac specific code in GenericCommands.cpp to help avoid some of the confusion. It will still be a little confusing to people until they look further (such as the comments for the enum values of EModifierKey.Control and EModifierKey.Command) but I don’t have a solution that isn’t littering the code with “we automatically translate control and command”.