There are two main things here.
You can contribute with the i18n by translating Knowage through our public Zanata instance! https://www.knowage-suite.com/zanata/
As soon as possible, I will add Arabic language in Zanata. From there, you will be welcome to start translating Knowage!
As iftikharalam said, this is the main issue. At the moment, this option is not available yet out-of-the-box. My suggestion is to contact Knowage team (https://www.knowage-suite.com/site/about-us/contact-us/) and ask about it.
The Arabic (Egypt) language has been added and your account has been added as translator.
Take a look here: https://www.knowage-suite.com/zanata/language/view/ar-EG
Anyway, there is still an issue about RTL support. Supporting Right to Left is absolutely feasible for Knowage, but it required some work to do. Again, I will suggest to contact https://www.knowage-suite.com/site/about-us/contact-us/ to see how to collaborate on this.