Well, that’s some progress at least…
Sadly it seems irrecord (and mode2 and irw as well) is not compatible with the gpio-ir module. 
You can read something on it regarding Stretch and Buster here (https://www.raspberrypi.org/forums/viewtopic.php?t=235256), but I think it is the same problem we are facing here.
Bugs have already been reported with patches for Lirc 0.9.4c-9 (https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=930485) and 0.10.1-5.2 (bugs.debian.org/cgi-bin/bugrepo … bug=931078)… but we are on Jessie and that means Lirc 0.9.0~pre1-1.2 and I guess there will be no patches for this version.
So, for a short-term solution it would probably be necessary to build your lircd.conf on a another system where irrecord (still) works.