Are antithetical couplets mostly untranslatable?
It is called 無情對, The sentences don't make sense even in Chinese, therefore, there is no way to translate them into English

無情對


It is a special couplet form, the upper and lower lines are not related to cohesion. But each single &quot;character&quot; in the upper couplet match each single &quot;character&quot; in the lower couplet

Example:
[公 vs. 法] (公 = fair; 法 = law) - both noun related to rule
[門 vs. 國] (門 = school; 國 = nation) - both noun related to gathered people
[桃 vs. 荷] (桃 = peach; 荷 = lotus) - both noun related to plant
[李 vs. 蘭] (李 = plum; 蘭 = lily) - both noun related to plant
[崢 vs. 比] (爭 = fight over; 比 = compete) both verb related to competition
[嶸 vs. 利] (榮 = glory; 利 = profit ) both noun related to success
[日 vs. 時] (日 = day; 時 = hour) both noun related to time
Most importantly, these couplets rhyme in Chinese but won't be in English. That's why you can never translate a 無情對 into any other language
A question asked by me related to 無情對
Of course, you can translate them word for word, but the end result will not be coherent sentences and certainly not a couplet anymore.

公門桃李崢嶸日 (The day the students of the honorable you shine)


法國荷蘭比利時 (France, Netherlands, Belgium)

As for normal couplets, you can translate them into complete sentences, but they will not rhyme and won't be couplets