Could you move the original barge sinking to the Voice of Rots bayou and then link the inherited speak with dead ability to the Voice of Rot. The magical matrix weapons is something that could fit in with either the Ob or Pemberton , there is mention of arcane fusils which the Shining legion use and I seem to remember being an alternative to cannon but at much higher cost. Could be a useful weapon in the bleak gate.
The ship with risuri cannon seems unlikely to be Danoran they have more and better cannon, so perhaps it was a pirate ship you could give some sort of chance to uncover the men who sold those cannon to pirates, possibly those Ber-ish Orc pirates and raiders
