So I just finished building my cartographers guild, which is great and clear about how to see where the pets are on the map. Now I have the problem of not being able to use any of my actual catchers, whether the guild is turned on or off. This was not a problem before the guild was built. I don't know if this is a bug, but I figured I would ask here first in case I'm simply missing something. I am able to use the observers, though they aren't really needed at this point.

When you can't use your catchers usually is because you don't have space for more pets, pregnant pets count for 2 at the moment of conception.

Another problem is that you haven't purchase licenses from the state store, always keep 3 as they are 3 catcher to send.

Otherwise click on the orange words that says 'Hire one for 200 silver'

Hope that helps :)

Another reason could be that you ran out of licenses. 

Where do you find the blueprint for the cartographer's guild?

You get it the same way as all other blueprints and schemes. There are a few options:

1, You can find in while exploring islands with your pets
2. You can buy it in Item Trades from other players.
3. You can look around the Giveaway forum, often people give away items they don't need. This can include blueprints of all sorts.

Just for completion's sake, I will add that some other blueprints you can buy in the State Store, but I would strongly advise against ever doing that since those items are terribly overpriced in there.