So you contact the peasant that supplies oats for the horses. "When you
went into the castle was there 10 or 100 men?"
As this game is fairly strategic, and the tactical options are limited
I don't see that seeing inside structures is a problem.
I also don't see why you can't get full reports up until you
leave a province, as there will always be people to ask (those same
people that can be recruited).
Large amounts of troops tend to be noticable, if Feasel has
200 men in another stack that we can't see directly, we might be able to
tell from food usage, sounds, etc. Approximately how many people are inside.
Also as far as I know, medieval castles tend to be fairly open in regards
to peasants, etc. Coming in for trade, etc. The lord had a responsability to
protect the common men, and thus it creates a security leak.