"examining the new task boards found within any Adventurers' Guild, players may view and undertake the tasks of Eorzea's guilds."

The TASK BOARDS are found in the Adventurers' Guild, and There are 19 Eorzean Guilds, so im sticking with 19.
It's not 1 per adventurer's guild.

Oh Hey Mack! Nice to know someone else noticed.