Ta for that. Especially for the link to Snoop, which my son swore up and down was not a real thing: "The pros use soapy water, Mum, I promise you that there is no such thing as specialised leak detector fluid." Of course, locating some in rural Ireland is not going to be easy- there's one distributor in Dublin, and Dublin is on lockdown right now.
I have two manifolds at present- the one that came with the regulator, plus one more. I don't really fancy trying a splitter- each manifold has its own bubble counter, and as my tanks are all over my living room, it's good to have some kind of central visual feedback, which I imagine would be a little more awkward with a splitter (I know inline bubble counters are a thing, but I don't fancy having an octopus of CO2 line with inline bubble counters- the manifolds would make a far neater job of it).
I'm still wanting a good understanding of what I'm doing here. It's frustrating to ask "can I use a bunch of manifolds?" and have people suggest that I simply buy another regulator without really answering my question. I may well buy a second regulator eventually, but that doesn't mean I don't want an answer to my original question.
So, again: what are the potential drawbacks running several manifolds, beyond the obvious "you will drain the CO2 cannister more quickly"?