Why a single system
The temptation when shipping a multi-script product is to fork the design language per script. Resist it. A single system with explicit RTL primitives is dramatically cheaper to maintain than three near-identical-but-different systems.
What is shared, what is forked
Type ramps, color, spacing, motion, icons, and component anatomy are shared. What is forked: typeface per script, line-height scaling for Arabic and Sorani (which run taller than Latin at the same point size), and a small set of directional icons.
The unsexy win
The biggest productivity gain was a single Figma library with token aliases that swap fonts and direction based on a top-level locale variant. Designers stop thinking about "the Arabic version" and start thinking about the product.