Use what you’re comfortable using. All I can advise is what I know works. Kanaplex and furan 2 won’t crash your bb. Maracyn and maracyn 2 will. But, if the other fish aren’t showing signs of columnaris, I’d hold off using meds. If you could move the snails and add the salt before you leave, you may be ok. Let me say this about furan 2: Furan and Dioxin are two of the worst poisons (in their purest forms) in agriculture. That being said, Furan2 is NOT pure Furan. It is a tiny bit of a bound molecule. If every aquarium in the US dosed furan2 at the same time and dumped the “used” water in the same hole, there wouldn’t be enough furan to measure. I could go on and on but I won’t. I’m tired.
I wish you could see the photos. . 4/6 remaining Cories appear to have perfect fins & are spawning & loving life. 2/6 have fins that are ragged & even appear like the front hard fin cartilage is completely separated from the rest of that fin like the fin has disintegrated.