It appears Jan asked for staff assistance on this awhile ago, my apology for the time it's taken.
It is most certainly possible that not every planet in a government would know exactly where any hidden planets were, even if said worlds were construction planets. I believe (it's this way for my group) that only those who do need to know, know. Most planets will most certainly not need to know where a top secret military installation was located.
Captured ships could know the location of the planet, sure, but again, hidden or hard to find planets would be highly protected assets, only those who needed to know would know. Not every ship in TNO's navy is going to know the location of Bastion. The larger a government is, the less chance any given craft is going to know about said planet. Command-class ships, though, have a larger chance of knowing where the planet is.
Very few politicians know the location of top secret military bases, but top level commanders could. Not to say that a general would know the exact cords, in all probability he just knows of its existence and estimated location. He doesn't pilot the ship himself, a crewmen does that. I don't know what Joren was, so I can't comment further.
TNO has captured a world that probably wouldn't know where the planet was - though with that world they could have gotten personnel who new, low chance there. TNO has captured, as I understand it, several command cruisers - high chance there, though the data cannot be used until the RP is completed. They have also captured one of the big three, nice chance there.