This package adds Atom support for everybody's favourite array-wrangling crypto-language.
No APL symbol fonts are bundled with this package. Anybody interested in APL is assumed to already have supporting fonts installed. Furthermore, Windows and Mac OS both ship with fonts that support APL symbols (Arial Unicode MS and Menlo, to name two), so you'll probably be fine.
If the characters aren't displaying correctly, try installing any or all of these:
Side-note: I recommend installing Symbola anyway, even if you think you don't need it. Noto Sans Symbols is highly‑recommended as well. Install them both to dispel tofu!
Good catch. Let us know what about this package looks wrong to you, and we'll investigate right away.