@jooyeonkang Yes, it doesn’t make sense at all if you only took on the half-end on my response.
As you just stated that you have your own policy about checking the word amount, that’s a little bit different. There’s a chance that there will be no difference (in case if your buyer has the intention to give negative review) between not sending the translation that covered by your gig and cancelling the order. Both will surely hurt your stats, and that’s not good.
I just checked your translation gig and you have completed 1835 orders perfectly.
Let me show you a bit about the math if you get 1-star review:
[(1835 orders * 5 stars) + (1 order * 1 star)] / 1836 = 4,9978 (this is your gig’s rating)
Please have a look on below-image:

This seller got 1-star review out of 283 reviews with 5-stars.
Do you see that round up law does apply here?
You have 4,9987-stars (please disregard the frational numbers at this moment), and it will be rounded up to 5-stars!
But still, they way to run your business is up to you. I have show you the math and the real evidence, and that might be enough for your consideration for not cancelling the order. You’re in the “safe zone” and should not cancel the order by any reason. You need to show that you have your own policy and so you won’t get the next “cheating buyer”.
Doesn’t it make sense now?