Question about attack speed

The Rune does breaks speed cap, possibly at a -2 speed. Beast tamer's buff can also break speed cap but seems to have an issue with green pot because they don't seem to stack and counter each other.

The swift rune is -3, the two other than the healing one are -1, those should potentially let you break cap as well, maybe? Unless green pots and swift runes are handled differently for some reason.