RoboFont version: 4.5 (build 2410282152) - Monterey 12.7.6
The generated glyphs inherit the base glyphs' codepoints. For example: one.circle will have the same codepoint as one, leading to suprises in the Space Center, i.e. one.circle being displayed instead of one.
I can't seem to find anything about Unicode handling in the documentation by the way.