The fastest way to spot an agency that does not work in Arabic is to look at the Arabic site. Not the layout — anyone can flip a grid. Look at the headline. If it reads like something translated, it was.
Arabic headlines are not English headlines reversed. The rhythm is different, the density is different, and the register that sounds confident in English often sounds either stiff or oddly casual in Arabic. A line that takes six words in English usually takes four in Arabic, and the four have to be chosen, not converted.
Then there is the typography. Latin display faces have a century of advertising behind them. Arabic display faces have their own history and it is not the same history. Setting Arabic in a face picked because it 'matches' the Latin one is how you get a brand that reads as foreign in its own market.
The fix is not complicated, it is just more work: write both languages from the brief, not from each other. Draw both scripts in the identity phase, not as an afterthought. Have a native speaker who is a writer, not a translator, own each language.
You will spend more. You will also stop sounding like a company that arrived last week.