In order to modify the
accel-cmd -p 2004 show session
output to fit a common needs i'd propose a config option like

set vpn cli sessions-columns "list of comma separated list of statistics columns available from accel-ppp"

for example:

set vpn cli sessions-columns "vrf,ifname,username,calling-sid,called-sid,ip,rate-limit,type,comp,state,rx-bytes,tx-bytes,uptime"

which should set the appropriate option in [cli] section of /run/accel-ppp/<vpn>.conf where <vpn>=l2tp, pppoe, etc depending on technology:
[cli]
sessions-columns=vrf,ifname,username,calling-sid,called-sid,ip,rate-limit,type,comp,state,rx-bytes,tx-bytes,uptime