I’m pretty sure that the kvfiledump role is for “emergency” recoveries like this… I don’t think it’s part of a supported backup/restore path. I suspect you would need to build your own tooling to write these K/V pairs back to the database again (perhaps as part of your application that’s already connecting to FDB.)
The fdbbackup and fdbrestore tools (and the disk snapshot backup alternative) both have supported restore paths, if you want a more reliable way to do this in the future.