man I would use steel shielding at least for something connected to explosives, that's pretty ratchet as far as applications and risks, based on the lack of metal I will assume susceptibility is not considered in the design, connected to explosives.
IMO incompetent. You should also use shielded wire and RF shunts on the detonators, really they should form a conductive seal with the shield and be part of it. A small powder charge should have no problems rupturing the shielded detonator casing. This is made with speaker connectors and wood.
This is something you want magnetic shielding for. Also interlocks. You should post a PCB so it can be likely fixed. The igniter wire should also be brazed to the conductor wire so you can't get a loose connection. A spark can set off powder geometries of a certain shape, so you can lower your initiation threshold from a heat requirement of the wire to a spark ignition (that is unreliable but possible). I hope you did not twist those initiators on, particularly when you have corrosive pyrotechnical compositions that likely use sulfur, chlorates, etc. The spark should not be remotely able to occur anywhere near the powder, so you want lead wires that leave the detonator and connect some where else.