<Snigfarp> You are also correct :)
Rule nr. 14 is difficult. I would translate it thus:
The castle can prevent, just like a third piece, that when a soldier stands on 2 (f.i. e4) and an enemy is on 3 (f.i.e3), it (the soldier) could be killed.
So it contains no new information.
Notice that Lin. uses the latin word "trio" wrong, and this makes an accurate translation difficult. I think my translation of the word intercludere is correct because else the rule COULD perhaps mean something like: the castle is hostile to all pieces. We don't want to go there :) Actually I think playability should be a factor when translating the rules.

Strange is rule nr. 9: "etiam Rex" doesn't mean "except for the king" (like Smith) but "EVEN the king".
Should we conclude that the king is also killed by two pieces except in and around the castle? I don't think so because it would contradict with rule 3 and 5. If two pieces were enough to kill the king, then the king CAN be killed when he is on c3 with no pieces on a3, b3, c1, c2. Namely when an enemy is on d3 and another one moves to c3. And since rule nr. 5 says the kings exit can't be prevented in this situation, the king MUST always be captured with 4 (or 3 with the castle).

So: either Linn. meant "praeter" (except for) in stead of "etiam", or he meant that even the king should be taken off when captured.