I've noticed the Keyboard Maestro Engine is constantly writing to disk - about 65KB/sec. Haven't traced the location it's writing to, but is this normal?
I suppose one of my macros could be firing and producing log messages but that seems kind of egregious.
The only files that seem writable that the process has open are these:
I don't know what iStat Menus shows, so that's hard to know what it is even refering to,
Looking at Keyboard Maestro Engine in Activity Monitor, Disk view, my “Bytes Written” went up by 0.1MB after several minutes (while using my Mac normally, including triggering various macros), so that is clearly a lot less than 70 KB/s (which is 4MB/minute).
So I would suggest you start by looking at what Keyboard Maestro is doing, perhaps first looking at the Engine.log file (Help ➤ Open Logs Folder). Obviously if it is doing a lot fo stuff continuously, that would change things. There are other reasons why Keyboard Maestro might be working hard even without log messages (such as servicing requests from the Keyboard Maestro editor, or running a long running macro). Checking if there are macros running (in the status menu, Cancel submenu) would be another place to look.
All sorts of actions could in running macros could write lots of data obviously.