The cheapest possible test
Open the Arabic version and read it without comparing. If it feels like a translation of something, it is — and the reader who only reads Arabic will feel that on every page without ever filing a complaint about it.
A corporate site serving an audience that reads both Arabic and English, where the Arabic version is not a courtesy — a meaningful share of the people making a decision about the company will read it in Arabic first.
The common approach is to build in English, then add Arabic near the end. The result is a version that reads as a translation: mirrored layouts that were never designed mirrored, typography tuned for Latin, and navigation that feels slightly wrong in a way readers notice and cannot name.
I designed both directions in parallel rather than sequentially, reviewing every layout in Arabic and English as I built it. That surfaces the direction-dependent assumptions while they are still cheap to change.
A bilingual site where Arabic and English are both primary: structural RTL support, typography tuned per script, navigation and hierarchy that hold in both directions, and responsive behaviour verified in each.
Open the Arabic version and read it without comparing. If it feels like a translation of something, it is — and the reader who only reads Arabic will feel that on every page without ever filing a complaint about it.
What it runs on