The spring seat is the part of the absorber the spring sits on when it's assembled together. On the GTI, the front springs are quite tall so the lower spring seat isn't an issue. If you use the Wira SE one it'll drop the front of the car quite a lot. Just fyi, I scraped every bump I ever came across because of this setup.
And the rear height is the same for all Wiras so front low back high = tonggek and it's fugly, handles like shit and quite a nuisance.
Sounds like your batch was one of the 2nd last. The final batch didn't come with anything except muffler and 16" rims. Keep those front springs! Precious commodity bro!