I don't see anything in that log that would suggest why the bot would close.
Typically, if the bot randomly closes, it's due to an auth issue, such as your session being expired or possibly the auth server going down. That type of error should be logged though, so I don't have any suggestions for you other than check your Sandboxie settings to make sure you have enough space for the game and bot to run properly.
Post you setup, I used to use sandboxie, but found the overhead it takes I could use that to run another bot. So I stopped, but I've neve had issues with sandboxie.
You gotta make sure each bot runs with the PoE sandbox.
IE.
SandBoxie 1 - > PoE1 -> bot
Sandboxie 2 - > PoE2 -> bot2
Each bot per PoE has to be ran from that poe's sandbox, and direct connection for all the bots, don't send them through a *** each, they will close.