I think maybe blunderbusses are a bit too up-close, since they're for cavalry and stuff. The Islands are quite mountainous, so I don't know how much cavalry is really used. Good idea to consider though.
Maybe we could try and fix up the more obvious oversights on the Victoria too? For a magazine-fed weapons we're stuck with compressed air (I'm still impressed how inspired a reach that was) since there's no integrated cartridges around. The actual magazine mechanism itself could be stopped from jamming so much by adding a U-bend in the shape of it, which alleviates some of the problems that they had without having to compromise muzzle velocity. The removable air canisters was a good idea though, otherwise the guns would be basically disposable.
But that's revision level stuff. What if we were to have a crack at artillery shells? It makes indirect bombardment actually viable, which would do wonders at stopping advancements towards our territory. Timed fuses can be done relatively simply with a cylinder of gunpowder wrapped in thick paper. Then we'd just have to put the fuse in a shell with shrapnel, and when it's reasonable close to the target... BOOM. Hell, the simplicity means that operators could probably change the fuse length on the fly, since all they have to do is cut it shorter and then jam it in the hole that the fuse ignites through.
Ninjad: I kind of doubt that. Why would they work together? Most likely just a coincidence that both the uncultured swine and misguided pretenders don't fully understand us.