Look here, between I2VPN Trusted Main and I2VPN Client there is a set of unknown, untrusted, random computers which is not owned by either you or me who just route this traffic without any interference (it's not possible to interfere), when it reaches either your computer or main, both don't know anything except your & main's I2P addresses, this may be highly technical but if you research it, you will know what I am talking about.

Regards,
Pkzone