RBS 56 BILL is really weak in v2. I think they forgot to increase the values from v1, it stayed at 30C. For comparison, a HEAT rifle grenade in v2 has 30C.
Tank Breaker increased from x30C to 90C (might be a bit weak as well, but that was a fictional weapon at the time).
Even though RBS-56 was designed for top attack, it was still a modern powerful HEAT warhead designed to defeat ERA (by using explosives that had higher detonation velocity than what was expected to be used in ERA tiles)
I tried to find info on warhead diameter, but only found for BILL 2 (110 mm main warhead)
The picture is wrong as well. That's not how the tripod looks. Even in 1989 (v1 HWG) there should have been pics available. Big disappointment for me who did military service using the RBS-56 in 1989.
Sorry for the rant!
For comparison or adding new weapons, I would use warhead diameter and "generation" to make up stats. I.e a 100 mm warhead from 1988 has higher penetration than a same diameter warhead from 1973.