Yes, you are eligible for an extra 12 months. Remember, that RO participation doesn’t count towards the regular IEC agreement.
This means that even when it says, “those who already participated in IEC twice are no longer eligible to apply”, you’re exempt because you participated under RO the second time.
The increased maximum stay from 2-3 years is great news for anyone currently holding a 24 month IEC visa, but it is worth noting that this is not a work permit extension, but rather an application for a brand new work permit that provides you 12 more months in Canada.