First if all, I am making an assumption that the close tab buttons cannot be moved... Having become used to Firefox browser tabs and some tabbed text editors that have their close tab buttons situated on the far right of the application window I would like to have this optional position available in Kate. Firefox allowed configuration of this option so that users could have the close button on the tabs or on the right hand side of the window as before. The FF dev.s changed the default position of the tab close button but retained the option for the previous functionality. My other editors also have the close tab button on the far right. I have grown used to being able to close tabs by clicking on a button that is always in the same position on the far right. It is both familiar and useful.
Created attachment 102472 [details] mockup of alternate tab close position
Firefox doesn't have that UI anymore, and Kate uses an intelligent tab sizing system such that if you close one tab, the next tab slides in to take its place and that new tab's close button is right under your mouse, so you can just keep clicking to continue closing tabs. As such, I don't think the proposed idea is needed, since it can already be accomplished with the current UI.