It was necessary to create a second font because of TrueType's hard limit of 65,536 glyphs per font.
Along with Fontforge looking for Unifont, I recommend that it now also look for Unifont Upper as a fallback font. Unifont Upper will contain glyphs in the Supplemental Multilingual Plane (Plane 1) and Plane 14. I do not intend to have any glyphs in Plane 2; that range is best handled by Wen Quan Yi. You can see a list of the scripts that Unifont Upper currently contains at