This has happened a couple of times (also to my boss) - but once in a long while, Kate will just switch over to right-to-left input.
We've searched for the menu command or keyboard combination that triggers this so that we can return to left-to-right input, but we've pretty much had to resort to restarting Kate.
What is the command for this switchover?
I think you are getting bitten by this bug.
Some observations from the comments: