anything with actual break-through pin holes, the easiest way to fix it is brazing it. sealers won't hold once its broke through no matter what
i dunno i avoid all that shit, i do a muriatic acid soak using a rubbermaid with like 1" in the bottom to really burn it all out good, then i strip the paint in the affected area, then a couple rinses, then braze it, coat the inside with half gas half oil mix, sand, bondo, sand, primer, paint.
i've saved some pretty gnarly shit. This ninja 250 had like 1/4" rust holes that i had to weld roofing nails to close up, someone had tried a bad JB weld and bondo job on it and it was all smashed up. When i was done you could definitely tell it had been patched, but it didn't leak and got the jerb done. More time with the bondo and i could have made it nice but it was a $200 commuter/beater bike so who cares.