I think the Spanish are confused about what are terms and are demands.
Terms are what two or more parties of roughly equal position and strength can agree on, or alternatively when one side is clearly stronger but it is willing to concede out of good will.
Demands are what you can make when you clearly have the upper hand and the other side is in no position to do anything about it .
At this moment Spain should be happy to be able to negotiate terms, and is in no conceivable way in any position to issue demands at all.
And just to make it even clearer: wanting 30 ports (or even 50 as i also heard) currently held by the other side while losing multiple ports daily is not negotiating terms, it's is making demands you can not ever back up.
PS: People should stop shouting about reducing any nation to 1 port, it's bad for the game and no fun for anybody. Conversely, Spanish captains should stop taking these seriously as the leaders and representatives of Dutch and British have repeatedly stated that reducing to 1 port is not the goal.