TOPIC:

What do the setting Render Quality and Text is right-aligned exactly do?

Any setting selected under them does not change anything in the PDF.
There is no visible difference in the PDF once these settings are applied.

What should be the output of these settings?

text rtol only applied in arabic languages, helps to ensure texts are right to left.

render mode:
image is not smooth, when render mode is 0,
otherwise, image do smooth scaling ( only applied when image define smooth rendering ).
it is almost no different for colored or grayed photo.
obvious different when image is mono,.