My port shows the keys on the automap when the 'k' key is held down. This allows the keys to flash when the cheat button is mashed helping to be able to see them.
I'm really sorry. I fixed this in my port in 2015 and for some reason I failed to publicise this.
https://github.com/jeffdoggett/Doom/commit/14546b818077bcd2b51297c8f2ac05a9cadc2b15#diff-7d32a55729cba3784b056944307ec02973678523890c77f51e0ce45b0df65366