Not sure about SSRS 2005 but in SSRS 2012 - the Direction property can be an expression. In SSRS 2012, I would include information about the direction of the text within the dataset and use that in an expression for the Direction property of the text box to control whether it is displayed LTR or RTL

e.g. =IIF (Fields!Language.Value="Hebrew", "RTL", IIF (Fields!Language.Value="Arabic", "RTL", "LTR"))

Or maybe in your dataset you include a direction column that contains the value "LTR" or "RTL" and the expression becomes

=Fields!Direction.Value