Thats interesting, iv not got any triacs at hand to check with. What version firmware has your T7 got? Do you have a pic of its insides?
I purchesed it a few weeks ago from WAVGAT store on Ali but otherwise its unbranded.
It looks to be identical to yours in every way - same MCU marking, same board revision and layout, and same FNIRSI-TC1 message when you self test, without a firmware revision number when it completes.
I did some further investigation:
If you attach Triac with MT1 > Pin1, MT2 > Pin2, G > Pin3, it reports on screen with MT1 and Gate transposed.
If you attach Triac with MT1 > Pin1, MT2 > Pin3, G > Pin2, it reports the pin out correctly.
Some other connection combinations display correctly and some don't...
Maybe FNIRSI will fix the firmware
Oh, and these Triacs are BT136-600E, not B as previously mentioned.