They are used as components in building other glyphs.
gafsarkashabove-ar is used in gaf-ar and its varaints, gafsarkashcenter-ar is used in gafInvertedstroke-ar, and doublestroke-ar is used in lamDoublebar-ar.
If you use Glyph > Make Component Glyph for gaf-ar etc. it will build it using these components if available, otherwise it will do nothing.