I would love to answer this question if I know what does ''laisser à désirer'' mean in English. :) Do you know what does it mean in English ?

Salam Denis, I can't think of any Arabic expression that means same as "laisser à désirer" en French, but you can translate it into Arabic as "غـيـر مرضــي / يمكـن تحسـيـنـه" which translate into English as "unsatisfactory / could be improved".

بالفصحي : يَتْرُكُ مَا يَرْغَبُه بالعامية يسيب إلي بيحبه

يترك الأمور التي يرغب بها