Eagle is quite neat in some ways, which sometimes referred to as “orthogonal”.
So In Eagle the page frame is a symbol, which users can customise, and put their own fields into. This doesn’t translate to KiCad simply, so you get this sort of orphan fields. In my converter tried to convert the page frame to a KiCad worksheet, but this doesn’t always work, and the custom fields are not supported.
I would convert the frame stuff manually, delete the “FRAME8” symbol, and set the fields in the schematic properties, to give a native KiCad style.