I would say that the modem supports them but they are not in use.
The output from my Zyxel VMG8924-b10a is exactly the same, but the synch stays constant while the SNRM fluctuates slightly, so I know SRA is not working.
Capability:
bitswap On
sra On
trellis On
sesdrop Off
CoMinMgn Off
24k On
phyReXmt(Us/Ds) Off/On
TpsTc AvPvAaPa
monitorTone: On
dynamicD: On
dynamicF: Off
SOS: On
Training Margin(Q4 in dB): -1(DEFAULT)