Current implementation requires using a single string and pipes to separate multiple passwords.
Not user friendly.
If it’s possible, it would be nice to have a set of text fields with labels indicating to which certificate the text field is associated with.
You can also use multiple Certificate and profile installer steps if you don’t want to list all with pipes.
Also, if you upload your certificates to bitrise.io using the Code signing & Files option in the Workflow Editor there you can manage the files & passwords in pairs, as separate items.