When placing an Arabic weight statement (e.g. "13g") followed by a tab and a percentage (e.g. "19%"), the weight declaration ("g" or "mg") moves to the percentage when exporting to pdf. Only when setting PDFX/1a:2001 is selected the output is correct. But this setting removes all layers and flattens transparencies so it's not very useful.
A workaround is to place a space after the tab (so on the left side since this is a right to left language).
See screen shot in attachment. On top = InDesign file, bottom = pdf created from this file using PDFX/4. The top line in the Indesign file has no space after the tab, resulting in a wrong placement of the "غ" (= Arabic "g") as marked red in the screen shot.