One discussed point in another thread is making rams available to all civs, I'd think that even if there are no accounts of the full ram vehicle for other civs allowing at least a basic form of ramming (a big trunk with fortified head) would make sense and balance it a bit.
As for torching, raiding was often done with regular cavalry on small towns and sacking with regular troops, so I'd see that as something reasonable too, though the mechanic would have to be well thought out.
Undermining tunnels, I could not find accounts for other civs except for Romans.