自2019年起，服務滿七個月，甲方給付乙方之考核獎金額度最高為乙方半個月
This part is missing from the English translation. And, I guess it is the contract @Zapman has not signed, right?
Add:
It was translated.
The maximum amount of Party B’s performance incentive is NT$ __________, which is the amount of Party B’s base half month salary.
I was employed from January 1st 2018 to July 31st 2019. August 1st I went to my new job.
So I completed my contract to the last day.
What exactly does that entail? lol
I don’t want to go to court or have lawyers up my ass.
Could any of this possibly give me a criminal record like if I lost in court or by refusing to pay them? (If they even wanted this to go to court for 5 grand)
No.
What they’re doing is illegal. They’re asking you to pay money based on a contract you didn’t sign. If they threaten legal action, they’re bluffing. You signed a contract and were paid based on that contract. And you’re not even at the damn job anymore. Block your old boss (or whoever is contacting you) on your LINE and cut off contact with them. They’ll move on because there’s nothing else they can do.
I second that.
They can try to give you a bad reputation in the circles they move in, which presumably overlap somewhat with the circles you move in. As for legal recourse, unless you concede that you agreed orally to the new contract, from what I can see they have nothing. And yes, I second Drew’s comment that it doesn’t make financial sense for them to spend far more money taking you to court (it would be a civil suit, not criminal) than what they think they could gain.
@yyy is right. They could try to poison your reputation. But (a) I don’t think they’d be very successful unless they made up blatant lies about you (which would be even more unethical) and (b) you said you’re already at a new job. Unless you’re planning to leave this job soon to look for another, then the rumor mill shouldn’t affect you too much.
But then maybe he could counter sue for defamation of character. 
Again, a lot of money, time and emotional energy would have to be put into that. But yes, if you’re willing to take the risk it is an option.
Oh, and, if they value pettiness over cash, they could file knowing they’re going to lose, just to be annoying. As the defendant, you could face extra paperwork (and a security deposit?) when going abroad. I really, really doubt they would do that.
What do you mean by paperwork or a security deposit?
It’s possible for a defendant to be required to jump through some hoops in order to cross the border before a civil case is concluded. I assume if you hand the money over to the court as a kind of bond (the amount the plaintiff seeks plus the court fee) and do the paperwork, you’re good to go. Ask a lawyer for details.
Again, I really don’t think that would happen to you.
I am guessing they are not open on weekends?
The automated message is all in Chinese too.
EDIT, I found their opening/closing times -_-