Bombard & Earthquake spells do physical damage as well but they do not reflect damage via RPD,
Chaos damage spells would hit physical resist 20% of the time, they also do not reflect. That part is working as intended.
I'd imagine Shield-Bash, counts as a "Spell-effect" since the shield has no base damage, and the damage done is additive regardless if you're using wrestling or an actual weapon, similar to Nerve Strike, as a weapon has no effect on the damage of shield-bash.