Others have pointed out the filter actions, but basically what you're running up against is a difference in philosophy between Quickeys and Keyboard Maestro.
With Keyboard Maestro, rather than give you a tool that operates on file names in the Finder, I give you three different tools, one to iterate through the Finder selection, one to change the case and once to rename a file, and you put them together like lego blocks.
So yes, if what you are doing fits exactly in to what has been provided natively, the Quickeys approach can be simpler. But as soon as you want to do something slightly different, then you have to do it in an entirely different way, or maybe it is not possible at all.
With Keyboard Maestro, if you want to change the case of all the lines in a variable, the same process applies. Or if you want to rename the files in a different way, the same process applies - you just adjust the part that has changed to match your new requirements.
And yes, that can be a jarring change from what you are used to, but it can also open up whole new things you can do that you could not before, and while it may appear more complicated initially, plugging together several less complicated facilities keeps things simpler as you expand the scope of what you want to do.