Love to be a Lab rat if it actually works 
Since you mentioned, you know what, I first built the system with the 3 terminals, and they were syncing all fine, until, I copy-pasted the wrong printing template into the KD template with HTML codes, and the task cannot be marked anymore, every time I try to mark it complete, it will crash the whole system.
SO I went a bit digging and found a database task that shared here
And after executing the task, it did clear all the messed up tickets on KD Task Editor. but that is when I started to have this sync issue. Thought I might share this as well if this can be helpful when someone from SambaPOS try to solve the codes side of things.
But Thank you again for the suggestion, it really helped a lot!