I can't really help at this point, but I can at least say it seems to be the same on the Archer C7 v2. I have actually not tested what the output of 'iw reg get' would have looked like on OpenWrt Chaos Calmer. But with LEDE 17.01.0 the output is the same as you posted.
In addition, the kernel log also shows something going on with the country code:
root@LEDE:~# dmesg | grep country
[ 15.077237] ath: EEPROM indicates default country code should be used
[ 15.077245] ath: doing EEPROM country->regdmn map search
[ 15.077261] ath: country maps to regdmn code: 0x3a
[ 15.765167] ath: EEPROM indicates default country code should be used
[ 15.765175] ath: doing EEPROM country->regdmn map search
[ 15.765191] ath: country maps to regdmn code: 0x3a
[ 22.705429] ath: EEPROM indicates we should expect a country code
[ 22.705438] ath: doing EEPROM country->regdmn map search
[ 22.705447] ath: country maps to regdmn code: 0x37
[ 22.705557] ath: EEPROM indicates we should expect a country code
[ 22.705565] ath: doing EEPROM country->regdmn map search
[ 22.705573] ath: country maps to regdmn code: 0x37