Welcome to the forums!

Lots of good stuff since EoF.
1: Why do the site cards have a low shadow number? I think it goes not higher then 3 or 4. With the older sets it can go as high as 8.
Sites from Shadows onward use a new system. In a nutshell, additional twilight is added depending on which region the site is in (sites 1-3 are in region 1, sites 4-6 are in region 2, and sites 7-9 are in region 3). Add 3 twilight if the site is in region 2, and add 6 twilight if the site is in region 3.
That keeps the twilight from getting too crazy since you can now choose any site in your adventure deck to play as the next site. It's also a hindrance to choke decks.
The rulebooks (accessible in
this thread) should explain things fully.
2: What is reinforce a token?
One of the new additions in the Hunters starter rulebook. I'll just quote it here:
Reinforce
This verb, used in game text, means to add a culture token to a card that already has a token of the same culture. You may choose any of your cards with the appropriate culture token if you have more than one. If an effect lets you reinforce more than one culture token, you may put them all on one card or divide them up however you choose.
Your card says, "When you play this possession, you may reinforce a
culture token." When you play this card, you may choose any of your Dwarven cards that currently has one or more
culture tokens and add another token to that card.