So both the TK-II Classic and the improved Universal 'J' version firmware have been corrected, and uploaded to the TK-II main page, as well as included in the XEL and XLD zipped compilation folders.
The classic version has moved from version 2.4 to 2.5, and is mainly provided to support the dual PS/2 keyboard aspect in the following products: TK-II-STEREO, TK-II-XEGS, TK-II-GS, TK-II-PB, and 1088XEL. This feature has been depreciated, and will no longer be seen in newer hardware such as the TK-II-PBJ.
The improved V2.6J version is the more universal TK-II firmware, and brings support for an AKI 'like' Console Function Key mapping, which is selectable between two modes: TK (Classic) and AKI. The AKI method is identical to what the Altirra emulator uses for the console and reset keys, thus making the transition between the two systems much easier. This mapping was adopted as the default for the 576NUC+.
To toggle between the two possible Console Key assignments, the key press combination of CTRL+ALT+E is used, with ALT+E displaying the current setting. This is non-volatile, so it will get restored to whatever the last setting was upon system power-up.
Another aspect of the V2.6J firmware that has hardware support in some of the newer TK-II boards, is the Arrow to Joystick mode, thus allowing the arrow keys to sit in for a joystick when selected. For the trigger, the Left-Windows key does the trick. Thus far there only two boards that support this: TK-II-PBJ and the ARROW2JOY-XLD adapter board for the 1088XLD. Pressing ALT+J will toggle the mode from standard arrows to joystick mode, and back again. It is a volatile setting, and will be restored to the arrow key default on a power cycle.