I am not a Grep expert, but my solution to this issue:

1- Make a paragraph style included with paragraph rules that match the size inside of the cell without the cell border, apply fill to the character color and paragrah rules with same color.

Then you can Find/Change your word text and change it to that paragraph style.

2- Make a paragraph style included with a nested style.

After you change your data and save it, try to check Update Data Source from Data Merge submenu

iidoido, there no magical way to do this. in InDesign ME you can design your layout for each English or Arabic on a separate files and don't forget to check Binding option: RtL or LtrR on document setup, depending on your language layout. after that you can combine two layouts design in one layout in Acrobat pro.

On windows, right-click properties and from the first row of dialog box ( open with- change )

Shift key + Pageup/Pagedown also work