Hi there @raqy,
Unfortunately text-align:left is hard-coded at the text renderer of the Newsletter.
See: mailpoet/lib/Newsletter/Renderer/Blocks/text.php at line 109;
It looks like that line of code is just providing a default if there isn’t any alignment styling set — if no text-alignment, then it will default to left.
Checking in the editor, that appears to be how it’s working as well:

Link to image: https://d.pr/i/s3kKJa
If you would like it right-aligned, then for now you would need to use the button to set the alignment in the editor.
Currently MailPoet does not officially support RTL — however there’s an open request and recent discussion on our feedback board below. It would be great if you could add your vote there to show your support for the enhancement (along with any comments):
https://mailpoet.canny.io/feature-requests/p/rtl-support
In the meantime, it would be necessary to either 1) manually set it to be right-aligned in the editor or 2) edit the code to change the default after each update.
And also it would be great if we could set the fonts, as they are also hard-coded for now.
Are you referring to the available fonts in the Styles tab of the editor?

Link to image: https://d.pr/i/DamFHi
There’s information about the available fonts here:
https://kb.mailpoet.com/article/176-which-fonts-can-be-used-in-mailpoet
If you wanted additional fonts added, or the addition of functionality for manually adding your own custom fonts, it would be necessary to request those via our requests board here:
https://mailpoet.canny.io/
Please let me know if you have any questions. Thank you!