KOReader doesn't integrate with Nickel metadata, so nothing would be expected to change in that regard. If you click on the plus icon in the top right you can "choose extract and cache metadata" although I'm not sure otoh if that also updates.
What are the names of the files you copied onto the device? Under file browser settings (leftmost icon in the top menu → settings) you can enable show hidden files and show unsupported files.
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