Customs Tax De Minimis - how strict are they? (Buying from japan)

Hello, so I regularly buy stuff from Japan because
they often have 2nd hand or limited not-for-sale stuff I can’t gey anywhere else.

My country’s de minimis value is around 200USD so I can go up to buying 20,000JPY without having to worry about customs taxing me— but I find out here in Taiwan it’s 2000NTD so basically 10,000JPY.

Unfortunately the proxy won’t let me change the price they present to customs and I’d rather not have to ship my splitting— are they very strict about the de minimis here? It’s practically just postcards and books, and the price I paid for doesn’t really match it’s product value.

Just want to know if anyone else had some experience with this.