I think redundant coordinators will work, you just have to have more than one in your bunker URI. Also I don't want to run this coordinator forever, this was just a prototype until someone made one in Rust.
But for now I think the signers are the biggest problem. There may be something wrong with nostrlib that causes it to not reconnect to the relay after a connectivity glitch, so they stop reacting to messages. Or at least that is something that seems to be happening with `nak bunker` too and it uses the same approach, but I can't figure out what the exact cause is. If someone can help find the bug that will be much appreciated. Or rewrite it in Rust.