Thank you for your feedback. You are correct that the extension is not language aware. However, there is an option/preference that can address your problem.

Please refer to the following page in the Wiki:

https://github.com/ushnisha/tranquility-reader-webextensions/wiki/005-Customize-Extension

You can set the "Text Align" option (under the "Text Display Preferences" section) to the value "right".

That should hopefully address your text alignment issue for right-to-left written languages.