I've created a basic AutoHotKey script that will launch Guild Quest, let it idle for 30 minutes so your Guildians can farm chests then quit the game for four hours before restarting the process.

You can find the script at:
Guild Quest Idler[pastebin.com]

The script is not ready to run as is!
You will need to set your path to Guild-Quest.exe as well various coordinates within your game. The coordinates are currently set to my system which is 1920 x 1080 and a game window size of 1600 x 1900.

Use Active Window Info (Window Spy) provided with AutoHotKey to find the necessary coordinates. My system required me to use the Absolute mouse position, your milage may vary.

Because Guildians can only defeat bosses while the game is active, yet the reset timer for the boss will continue to count down when the game is not running.

Like you, I want to farm chests. Sweet, delicious, Guildian giving chests. But, I don't want the game running 24/7. This gives me both.