It says so here but I can't find any official source or even references to an official source that states only 7 Seeds of Life were sent out by the FAR.

https://wiki.evageeks.org/First_Ancestral_Race

As per the article; "The information about them comes almost exclusively from their Classified Information Files and from Kaworu's 'good' PSP ending.", so it's gonna be in one of those two. These are both officially licensed material, I believe we have a translation of CI up on the wiki, if it's not in there, it would be in the PSP ending

Yes, but this isn't mentioned on either page:

They were the first extraterrestrial intelligence. The humanoid species, referred to as the First Ancestral Race, started to spread Seeds of Life throughout the Milky Way Galaxy. As of yet, we do not know their motives or for what they were aiming.

It is becoming evident that multiple Seeds were disseminated. Eventually, by force of sheer bad luck, two accidentally landed on the same planet: Adam of the White Moon, and Lilith of the Black Moon.

https://wiki.evageeks.org/Classified_In ... ranslation)

...but rather here, which is sourced on the page for the Seeds of Life themselves:

thread/8703/NGE2-First-Ancestral-Race-and-Seeds-of-Life

Reichu wrote:There were seven carriers that our home world's people boarded, you and me (1) included.
You and I were designers to the people whom we had brought with us.
After implanting into a world somewhere, we either bestowed upon them shapes as any form of life, or acted as representatives and chose the forms.

Reichu wrote:The "seven" struck me as a pretty blunt reference to "seven eyes of God" more so than anything else..

FelipeFritschF wrote:Yes, but this isn't mentioned on either page:

They were the first extraterrestrial intelligence. The humanoid species, referred to as the First Ancestral Race, started to spread Seeds of Life throughout the Milky Way Galaxy. As of yet, we do not know their motives or for what they were aiming.

It is becoming evident that multiple Seeds were disseminated. Eventually, by force of sheer bad luck, two accidentally landed on the same planet: Adam of the White Moon, and Lilith of the Black Moon.

https://wiki.evageeks.org/Classified_In ... ranslation)

...but rather here, which is sourced on the page for the Seeds of Life themselves:

thread/8703/NGE2-First-Ancestral-Race-and-Seeds-of-Life

Reichu#341191 wrote:There were seven carriers that our home world's people boarded, you and me (1) included.
You and I were designers to the people whom we had brought with us.
After implanting into a world somewhere, we either bestowed upon them shapes as any form of life, or acted as representatives and chose the forms.

Reichu#341250 wrote:The "seven" struck me as a pretty blunt reference to "seven eyes of God" more so than anything else..

That last part has me thinking, maybe that's why 7 is considered a lucky number in Western cultures.

FelipeFritschF wrote:Yes, but this isn't mentioned on either page:

They were the first extraterrestrial intelligence. The humanoid species, referred to as the First Ancestral Race, started to spread Seeds of Life throughout the Milky Way Galaxy. As of yet, we do not know their motives or for what they were aiming.

It is becoming evident that multiple Seeds were disseminated. Eventually, by force of sheer bad luck, two accidentally landed on the same planet: Adam of the White Moon, and Lilith of the Black Moon.

https://wiki.evageeks.org/Classified_In ... ranslation)

...but rather here, which is sourced on the page for the Seeds of Life themselves:

thread/8703/NGE2-First-Ancestral-Race-and-Seeds-of-Life

Reichu#341191 wrote:There were seven carriers that our home world's people boarded, you and me (1) included.
You and I were designers to the people whom we had brought with us.
After implanting into a world somewhere, we either bestowed upon them shapes as any form of life, or acted as representatives and chose the forms.

Reichu#341250 wrote:The "seven" struck me as a pretty blunt reference to "seven eyes of God" more so than anything else..

After reading about degrees of canonicity for Eva, my understanding is that the only parts of the NGE 2 game for PS2/PSP are the "Classified Information" sections that come from a 10 hour interview with Anno or something like that. And that the endings are pretty much just different versions of the original story done by the studio.

So, is the "7 seeds of life" thing not really canon then?

You are entirely missing the point of those guidelines.
The highest applicable information is the one that is relevant and overrules the things below; things that are in lower tiers, for which there is no explicit mention or implicit suggestion otherwise in higher orders can be taken as canon when discussing lore.

also please stop obsessing so much about the canonicity tiers; it is, frankly, a bit weird how much stake you put into a classification made up by fans