The high speed tracking thing seems to be a bug in the hand controller, or something undocumented that EQMOD doesn't do. There is no G110 command to tell the mount to return to microstepping, so AstroEQ dutifully obeys and continues in the current mode.
I suppose I could change back to microstepping mode automatically after a :K command is received, but without investigating whether that would cause problems with EQMOD, I'm not about to jump into doing it.
If you want to try it out, I think from a cursory glance, the following should work:
(1) Find the decodeCommand() function
(2) Scroll down until you find the case statement for 'K'
(3) Add the following line just before the break; statement for 'K':
cmd_setGVal(axis, 1);
That should return the internal variables to microstepping enabled slew when the :K command is issued. It won't immediately take affect if done here, instead it will take affect next time the :J command is called.