Nice catch!
The Conditions section says:
Entangled: The character is ensnared. Being entangled impedes movement, but does not entirely prevent it unless the bonds are anchored to an immobile object or tethered by an opposing force. An entangled creature moves at half speed, cannot run or charge, and takes a –2 penalty on all attack rolls and a –4 penalty to Dexterity. An entangled character who attempts to cast a spell must make a Concentration check (DC 15 + the spell’s level) or lose the spell.
While the Magic section offers:
Entangled: If you want to cast a spell while entangled in a net or by a tanglefoot bag or while you’re affected by a spell with similar effects, you must make a DC 15 Concentration check to cast the spell. You lose the spell if you fail.
Your point, Hervis, is, I think, totally correct. Only one of these can be accurate, and one of them is an error. Which one? I don’t know. Even if the specific is supposed to outweigh the general (without thinking what the actual mistake might be), I don’t see which of these is less specific or why.
Personally, I think the spell level should be added on, which means I favor the Condition text as well. I think there is definitely an error, though.
Cheers