Did you by chance base the oni dragon off of another unit, such as a type of militia? Because all the times they've cropped up its been in a place where you might normally see them. If you did, maybe if you just created the unit from scratch the problem would go away. That being said, it sounds like you did copy the dai oni and then change his sprite and so on. If you made a completely new unit instead it should let you do it without the javelin. For the record, I also was doing a quick test game of a normal nation with your mod on and found oni dragons defending provinces. Not sure that proves anything though.
Yeah, tasers aren't really overpowered on some things, they just have some idiosyncracies.
It would also be really convenient if all the different nations had different-colored score graphs to make it easier to tell them apart
