For some reason, on the second wallet that acts as a co-signatory for me - after executing the command, the transaction is not deleted, writes unknown see photo

And when try to send a new transaction, this error occurs-see the photo

It's RBF. Is your replacement transaction having a larger fee per byte than your first transaction?
What is this tool? how do I use it? The transaction is ready and signed by all cosigners, it remains to send out
Just a web utility tool for you to submit transactions to the network[1].
[1] coinb.in/#broadcast