Non latin glyphs not rendered

[ShaMan123]

When trying to render non latin chars (tried Hebrew and Arabic) I get a blank output.
font.hasChar('א') returns true.
However font.charToGlyphIndex('א') returns 0 and font.charToGlyph('א') returns the.notdef char.
Is this expected?
The specific font has copyrights so I can't share it probably.
Is there anything I can do to better triage this issue?

Expected

Using the native browser FontFace interface and CanvasRenderContext2d#fillText

Actual

Using opentype.js font#draw