According to these rules, if a portal has been breached into the opponent's zone, nothing prevents you from jumping in and capturing the Castle. That's the only restriction on Astral Gates; everything else is allowed. Basically, once the turns have crossed, the portal is likely breached, creating a theoretical passage between the Castles, and therefore, starting from the 3rd week, you can jump into the opponent's zone and calmly capture the Castle.
Added 10 minutes ago
Since there is no response to my message on the IRMG forum regarding version 1.7.9, and the discussion is taking place here, I will also express my opinion:
I suspect that version 1.7.9 of the generator does not generate starting zones correctly (a mountain in the middle of the starting zone or a sausage-shaped starting zone). Moreover, the old templates were used (which have not been updated for about a year).
Daniel and I played at least 20 games (probably more) on version 1.7.9, using the old templates, and it almost always generated such starting zones as I described - at least one of the two players definitely had this, the other might have been luckier.
We returned the previous generator, left the templates the same, and played a few games - it's like night and day; the above-mentioned problems are practically gone (at least, there was no mountain in the starting zone even once).
I will not argue with DVP or Moz - they know better what exactly might be influencing the above-mentioned problems (IRMG or the template itself). That is, this is a theory.
But the situation is as I described. That is, how it is in practice.
I admit that this may only be Daniel's and my impressions. And for everyone else, everything is generated perfectly in version 1.7.9, and there are no problems. Then the issue can be closed.
P.S. In my administrative work, there have been several cases when I said - this cannot be, because it never can be. And then it turned out that it can, if the stars align in a certain way in the sky. So here - let's sit down and carefully figure it out. I am not against new versions (either of the generator or of the templates). I just would like to have such versions in the tournament that have no complaints. And there will be no need to revert to the previous version in the middle of the tournament.