I have zero skills in APL, but my daily driver keyboard in 1986 was an APL keyboard on an IBM 3279 terminal. IIRC, the keyboard had Black ANSI legends plus red, blue, and I am almost certain green APL legends as well. Top and side printing for sure. This was very long ago, but I think it was a 3079 coax terminal. And the keyboard might very well have been 122-key.
Naturally I used it because it looked cool, and it came with the color display I needed for (again, probably) SAS on MVS.
- Ron | samwisekoi