I know nothing of the venom charger but if it is like any one that I have you have to "ok" the cell count in Lipo Mode so it should be impossible to make an error. You should also be able to see what each cell is charging at. If it was me I would try one more battery and babysit it and watch each cell voltage. It should not get over 4.20v per cell ever. If it does stop charging. It's a bad charger or it has some settings wrong somewhere

I'm really glad you had a Lipo bag. They are dangerous if not handled properly. Never had an rc battery blow on me but we did have a laptop battery get overcharged in the house and start a fire a few years back. Pretty much a total loss an everything inside the house between fie, smoke and water damage

Just be safe