I am American and grew up with US Customary / Freedom units, but I do design and engineering work in metric, so my brain sees feeds in inches/minute and I have to convert them to make sense of them. Carbide Create only shows the library in inches even if you are working on a metric design. It would be simple to have it show the units in inches and mm at the same time - could be coded in 10 minutes. Hope that they do this.
Until this is done, a work-around is to duplicate the tool libraries you are using and then editing the underlying .csv