I can suggest that you translate the website and tutorial videos to the biggest languages such as German, Russian, Spanish, Chinese, Turkish etc., that will bring more users too. It looks a little complex system for a person that don't know English natively.
I agree with you, translation of the rules/guides is a must. As a native Russian speaker, I could help with that, too.
Yes. Users can invite other users. Only 1 level.
Why is the referral program only available from the first level?
minho72, I ran into a problem when registering on the platform:

This happens when I specify an email in the format:
0x4f*****83213c1@ethermail.io